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Cavendish

Christa
Jungnickel

and

Russell
McCormmach

Cavendish

Christa JungnTickel
Russell McCormmach

Two gifted, eighteenth-century
Londoners, Lord Charles Cavendish
and his painfully preeminent son, the
Honorable Henry Cavendish, were
descendants of paired revolutions,
one political and the other scientific.
Scions of a powerful revolutionary
family, they gave a highly original
turn to their understanding of
public service. Lord Charles began
his career as a Member of
Parliament and ended it as an officer
of the Royal Society, and his son
Henry made a complete life within
science, in the course of which he
demonstrated skills that rank him

(continued on back flap)

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^avendish

CHRISTA JUNGNICKEL
and

RUSSELL McCORMMACH

THE AMERICAN PHILOSOPHICAL SOCIETY

Philadelphia, Pennsylvania
1996

Memoirs of the American Philosophical Society
Held at Philadelphia
For Promoting ( heful Knowledge
1 01 ume 220

Copyright © 1996 by the American Philosophical Society
for its Memoirs series, Vol. 220. All rights reserved.
Reproduction in any media is restricted. Publication of
this volume has been made possible by grants from The
Sloan Foundation, The Royal Society, and His Grace,
the Duke of Devonshire.

Front leaf: Cavendish Family; back leaf: Grey family.

Library of Congress Cataloging in Publication Data:

Junjjnickel, C Ihrista
McCormmach, Russell

Cavendish

Illustrations, bibliography, index, charts

1. Cavendish, Henry, and Lord Charles Cavendish

2. Science, history of 3. British science 4. Biography

ISBN:()-87169-22()-l 95-79391

For

Albert L. McCormmach
and

Marie Peetz McCormmach

TABLE OF CONTENTS

List of Figures x

List of Plates: Diagrams, Drawings, and Maps xi

Introduction: Problem of Cavendish 1

Part 1. The Dukes 11

Personal Characteristics 14

Career of the Duke of Devonshire 17

Career of the Duke of Kent 24

Part 2. Lord Charles Cavendish 31

1. Politics 33

Early Years and Education 33

House of Commons 39

Centleman of the Bedchamber 46

2. Science 49

De Moivre Circle 49

Royal Society 56

3. Family and Friends 63

Marriage and Money 63

Great Marlborough Street 66

Family of the Greys 68

Friends and Colleagues 69

Sorrows and Riches 75

4. Public Activities 85

Public Life 85

Westminster Bridge 89

Scientific Administration 93

Science 97

Part 3. The Honourable Henry and Lord Charles Cavendish 106

1. Education of Henry Gavendish 107

Hackney Academy 107

Peterhouse, Cambridge 108

Learning Science 112

Giardini Academy 126

2. Science 129

Introduction to Scientific Society 129

Science at the Royal Society 130

3. First Researches 143

Chemistry 143

Heat 156

4. Tools of the Trade 161

Instruments 161

Mathematics 168

Theory 169

5. Electricity 183

Capacity 183

Copyrighied malarial

Conduction 186

'I 'he Work 191

6. Learned Organizations 195

Royal Society 195

British Museum 205

Society of Antiquaries 206

7. Personal Life 211

Death of Lord Charles Cavendish 21 1

Charles Blagden 212

Monday Club 216

Part 4. Henry Cavendish 219

1. I lomc 221

Landlord 221

I [ampstead 229

Bedford Square 231

The Library 235

Clapham Common 237

Land Developer 242

2. Politics 247

The Royal Society 247

The Nation 256

3. Air and Water 259

Good Air 259

Witcr 264

Nitrous Acid 266

Atmosphere 267

New Chemistry 268

Water Controversy 271

Keeping Lp with Chemistry 272

Exactitude 274

4. Mercury 279

Cold 279

Heat 282

The Natural Philosopher 295

5. Sky 299

Collaborators 299

Weighing the Stars 301

Aerial Telescope 306

Indistinct Vision 308

Comets 311

Published Work 312

6. Earth 315

Triangulation 315

Krrors 316

Journeys 317

Bristol Harbor 328

Banks, Blagden, and Cavendish 329

7. Weighing the World 335

Density of the Karth 336

The Cavendish Kxperiment 340

8. Last Years 345

The Duchess and the Philosopher 345

Coinage of the Realm 346

Royal Institution 348

Institute of France 351

Wealth 352

End of Life 355

In Conclusion: Cavendish 365

Acknowledgments 372

Appendix: Officers of the Royal Society 373

Bibliography 374

Indexes 401

LIST OF FIGURES

(Between pages 218-219)

1 . William Cavendish, Second Duke of Devonshire

2. Rachel Russell, Duchess of Devonshire

3. Henry de Grey, Duke of Kent

4. Jemima Crewe, Duchess of Kent

5. Rents

6. Chatsworth House

7. Chatsworth House

8. Devonshire House

9. Wrest Park

10. No. 4 St. James Square

1 1 . Lord Charles Cavendish

12. Lady Anne de Crey

13. The Honourable Henry Cavendish

14. No. 13 Great Marlborough Street

15. Church Row, Hamptstead

16. No. 1 1 Bedford Square

1 7. The Cavendish House, Clapham

18. Chemical Balance

1 9. Battery of Leyden Jars

20. Portable Barometer

21. Mathematical Instruments

22. Mathematical Instruments

23. House of Commons, 1741-42

24. Westminster Bridge
23. Westminster Bridge

26. Royal Society

27. Foundling Hospital

28. British Museum

29. British Museum

30. Royal Institution

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LIST OF PLATES: DIAGRAMS, DRAWINGS, AND MAPS

I. Lord Charles Cavendish's Thermometers %

II. Factitious-Air Apparatus 1 53

III. Forces 172

IV Leydenjar 178

V. Hollow-Clobe Apparatus 184

VI. Artificial Electric Fish 188

VII. Map of Henry Cavendish's Homes 231

VIII. Map of Clapham Common 239

IX. Plan of Drains at Clapham 241

X. Eudiometer 261

XI. Apparatus for Experiments on Air 266

XII. Hudson's Bay Thermometers 280

XIII. Apparatus for Weighing the World 338

XIV. Plan of Clapham 342

XV. Coinage Apparatus 347

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INTRODUCTION

Problem of Cavendish

Henry Cavendish, 1731-1810, is described in
superlatives. Regarding matters of intellect and
fortune, he has been called the "the wisest of the
rich and the richest of the wise." 1 In his dedication
to science, he has been compared with "the most
austere anchorites," who were "not more faithful to
their vows." 2 His accomplishment has been
likened to the highest example: since the death of
Newton, England had suffered "no scientific loss
so great as that of Cavendish." ' He is described by
superlatives of another, darker kind as well.
Cavendish had a "most reserved disposition." which
was seen as "bordering on disease." 4 Cavendish was,
indeed, one of the greatest scientists of his century,
one of the richest men of the realm, a scion of one of
the most powerful aristocratic families, a scientific-
fanatic, and a neurotic of the first order. These
things being the case, it would seem that Caven-
dish's biographers are called upon to construct a
psychological portrait of a tormented genius.

We have taken a different approach
(though in concluding this biography we discuss a psy-
chological point). Cavendish's scientific achieve-
ment depended upon his talent, a given, but it
depended no less on his dedication to science, and
about this we, his biographers, can say something
useful. Until we looked closely at the life of his
father, Lord Charles Cavendish, 1704—83, we did
not have a firm understanding of Henry's. Coming
from a family of politicians, Lord Charles
predictably entered public life as a politician. It so
happened that while he was active in politics, he
also pursued science as a side interest, and indeed
at a certain point he left politics to devote himself
increasingly to science. His example was constantly
before his son Henry while Henry was a student
and later while he was giving direction to his life,
and it is clear that Henry followed Lord Charles's
scientific path. The public expression of the
scientific calling of Lord Charles and Henry was
their dedication to the work of the Royal Society
of London.

From the perspective of the larger society,
Lord Charles could have been regarded as over-
stepping the bounds of his station in life. Drawn to
experiment and especially to the instruments of
experiment, he was a type of technical man. His
aristocratic contemporary Lord Chesterfield made
a sound judgment for the time when he censored
the architectural expert Lord Burlington for having
more technical competence than his rank per-
mitted. 5 Within the Royal Society, however, both
rank and scientific competence were honored, and
Lord Charles and his son Henry are the outstand-
ing example of their union in the eighteenth
century. By the time Henry joined Lord Charles in
the Society, it had been in existence for a century,
and it had its hallowed traditions, but it still re-
tained a measure of its revolutionary' potential in
English society. Lord Charles Cavendish definitely
found support in the Royal Society for his move
from a traditional aristocratic career in politics to an
uncommon life of an aristocrat in science.

Lord Charles Cavendish's attention to the
affairs of the Royal Society was extraordinary by
any standard: no member of the Society, including
any of its presidents, gave as much of himself to
the organization of science as he did. It is critical to
the nature of this biography that the next member
of the Royal Society to do the same was his son
Henry. In this respect, of the two, father and son,
the father was the more original. At a time when
science did not yet offer itself as a profession, Lord

'J. B. Biot, "Cavendish (Henri I." Biographic Vniverselle. Vol. 7
(Paris, 1813), 272-73, on 273.

2 Gcorgcs Cuvier, "Henry Cavendish" This biographical writing
of 1812 is translared by D. S. Faber in Great Chemists, ed. E. Fabct
(New York: Interscience Publishers, 1961), 227-38. on 236.

'Humphry Davy, quoted in John I )a\ y. Memoirs oj the Life of Sir
Humphry Davy, Bart, 2 vols. (London, 1836) 1:222.

4 Henry, Lord Brougham, "Cavendish," in his Lives of Men of
letters and Science Who Flourished in the Time of George III, 2 vols
(London. 1845^46) 1:429— \7, on 444. Thomas Thomson, The History
of Chemistry, 2 vols. (London, 1830-31) 1:337.

^Quoted in Dorothv Marshall, l)r Johnson's I. one/on (New York:
John Wiley & Sons, 1968), 219.

Cavendish

Charles Cavendish turned to science, as he had
done earlier to polities, thereby crafting a version of
an acceptable profession for himself, the evidence
for which is as undramatic as it is indisputable, a
change of location of his committee work from the
House of Commons to the Royal Society. Lord
( lharles and his son Henry were the great councillors
and committeemen of the Royal Society. Councils
and committees are not ordinarily places of high
endeavor, and their members often feel impatient,
irritated, and stupefied; nevertheless, they are the
level of organization in scientific and learned in-
stitutions in which necessary tasks get done, and
they are where colleagues get to know one another
well and find out who has good judgment and who
takes responsibility/' The importance of Lord
Charles Cavendish for the history of science lies
not in any one achievement but in his forty years of
organizational work in science. Having made no
great discovery, he has entered the history of
science as, at most, a footnote, but in a biography of
the discoverer Henry Cavendish, Lord Charles
Cavendish necessarily appears with nearly equal
importance. Lionel Trilling's stricture "Every mans
biography is to be understood in relation to his
father" 7 may not be a practical guide for all biog-
raphers, but for biographers of Henry Cavendish, it
is indispensable. We have written this book as a
biography of father and son.

Historians of science know of Cavendishes earlier
than Lord Charles and Henry Cavendish. Richard
Cavendish, one of the Cavendishes of Suffolk from
whom the Devonshire* descended, was an
Elizabethan politician and professional student —
for twenty-eight years he was a student at
Cambridge and Oxford — who translated Euclid
into English and wrote poems including (and in
spirit foreshadowing our Henry Cavendish) "No
Joy Comparable to a Quiet Minde," which begins,
"In lothsome race pursued by slippery life." 8 The
namesake of one of our Cavendishes, Charles
Cavendish, a seventeenth-century politician, was
an important man in science: a solver of
mathematical problems, a maker of experiments,
an improver of telescopes, he corresponded with
the inventors of new world systems, Rene
Descartes and Pierre Oassendi. This Charles was
"small and deformed," but he had a beautiful
mind. In a time of violent controversy, he

advocated cooperation as the way to truth. He
subscribed to Descartes's maxim, "to strive to
vanquish myself rather than fortune and to change
my desires rather than the order of the world. . . ." 9
This Charles and his older brother William, duke
of Newcastle, who had a scientific laboratory, were
friends of Thomas Hobbes, the philosopher who
envisioned a state of war of each against all, and
who also wrote the most original scientific philo-
sophy in England. Hobbes tutored and influenced
three generations of the other main branch of the
Cavendishes, the earls (not yet dukes) of
Devonshire. He moved in the great houses of the
Cavendishes, Chatsworth and Hardwick Hall (both
of which our Lord Charles and Henry Cavendish
knew well), in the libraries of which he found the
true university that he had not found in Oxford. 10
By Charles Cavendish's time, science was not
exclusively a male preserve: a case in point,
Margaret Cavendish, duchess of Newcastle, wrote
a number of good popular books on the microscope
and other scientific novelties. She demanded to be,
and was, admitted as a visitor to the Royal Society.
She dressed like men and, in general, behaved like
a George Sand of science. Eor that, this original and
independent first scientific lady in England was
called Mad Madge. 11 In Henry Cavendish's time,
Margaret Cavendish Bentinck, duchess of Port-
land, also of the Newcastle branch of the family,
was a correspondent of Rousseau and a passionate
collector; at her death, the sale of her natural
history collection, second only to that of the pre-

Tewis Thomas, a redoubtable committeeman of science, has
remarked in various places on the indispcnsability and value of
committees and on the inescapable disruptiveness of human
individuality in the work of committees. E.g., in The Youngest Science:
Notes of a Medicine-Watcher (New York: Viking, 1983), 171; "On
Committees," in The Medusa and the Snail: More Motes of a Biology
Watcher (New York: Bantam, 1980), 94-98. Thomas's appreciation is
not incompatible with Alvin Weinberg's widely held opinion that
"committees... can no more produce wisdom than they can design a
camel." Reflections on Big Science (Cambridge, Mass.: MIT Press,
1967), vi.

7 From Lionel Trilling's introduction to The Portable Matthew
Arnold, ed. L. Trilling (New York: Viking, 1949), 15.
""Cavendish, Richard," DNB 3:1266-67.

'Jean Jacquot, "Sir Charles Cavendish and His Learned Friends.
A Contribution to the History of Scientific Relations between
England and the Continent in the Earlier Part of the 17th Century. I.
Before the Civil War. II. The Years of Exile," Annals of Science 8
(1952): 13-27, 175-91, on 13, 187, 191.

'"Samuel I. Mint/., "Hobbes, Thomas," DSB 6:444-51,
on 444-45.

"Gerald Dennis Meyer, The Scientific Lady in England 1650-1760
(Berkeley: University of California Press, 1955), 1-15.

Copyrighted material

Problem of Cavendish

sident of the Royal Society, Hans Sloane, took
thirty-eight days. 12 As if handing on the torch, in the
year Henry Cavendish was born, 1731, Charles
Boyle, the earl of Orrery died. This earl, whose
mother was Anne Cavendish, sister of the first duke
of Devonshire, was related to the great seventeenth-
century chemist Robert Boyle, and it was after this
earl that the instrument-maker George Graham's
invention of the machine to show the motions of the
heavenly bodies, the "orrery," was named. 13 (The
Cavendishes would make another connection with
the family of Robert Boyle in the year that Henry
Cavendish began university study, when Henry
Cavendish's first cousin, the fourth duke of
Devonshire, married Charlotte Boyle.) Other early
scientifically inclined Cavendishes include three
important Fellows of the Royal Society: the third
earl of Devonshire, the first duke of Devonshire,
who was tutored by the famous secretary of the
Royal Society I lenry Oldenburg, 14 and the youngest
son of the first duke, Lord James Cavendish.
English aristocrats who actively pursued science
were few indeed, and if a titled family was destined
to distinguish itself in the eighteenth century, it
was surely the house of Cavendish. Lord Charles
and Henry Cavendish's lineage was remarkable
scientifically as it was politically.

Our Cavendishes descended from two
revolutions, one political and the other scientific.
The Cavendish who became the first duke of
Devonshire took a leading part in the Glorious
Revolution of 1688, which deposed one king and
sat another. When compared with subsequent
political upheavals, the Glorious Revolution may
not seem all that revolutionary 15 (in part because
it was bloodless, hence glorious), but to the
British of the eighteenth century, it was the
embodiment of a radical change in human affairs.
Joseph Priestley, a scientific colleague of Henry
Cavendish and also a friend of revolutions, said of
this "revolution under king William" that before
the French and American "revolutions," it "had
perhaps no parallel in the history of the world,"
and for support he cited the philosopher David
Hume's view that this revolution "cut off all
pretensions to power founded on hereditary right;
when a prince was chosen who received the crown
on express conditions, and found his authority
established on the same bottom with the privi-
leges of the people.""'

The Glorious Revolution coincided with the publi-
cation of Newton's magisterial Mathematical Principles
of Natural Philosophy, or Principia, an event which
has often been singled out as the culmination of the
scientific revolution. By the middle of the eighteenth
century, the new political notion of a revolution as a
radical change, rather than a cyclical return, was
being applied to science, and with specific-
reference to Newton's Principia} 1 Today, we often
still speak of the scientific revolution, but when we
do, we recognize it as a long, complex historical
development and one that did not consist solely in
a preparation for the principles of mechanics and the
gravitational system of the world as laid down in
the Principia. Human understanding of the vastly
more complex operations of chemistry and of life
underwent profound reinterpretations as well, and
the subtle art of experiment was immensely en-
riched by advances in techniques and instruments.
That ingenious master of experimental apparatus
Robert Hooke was not less important than Newton
in preparing the way for Lord Charles and Henry
Cavendish. The same can be said of that pre-
eminent model of experimental persistence and
perspicacity Robert Boyle (who as an aristocrat
working in experimental science and shaping the
Royal Society was the preeminent model for them
in another sense). Together, the scientific power
revealed to the world by Boyle, Hooke, and
Newton and the political settlement of the Glorious
Revolution go far to make intelligible the remark-
able careers of Lord Charles and Henry Cavendish.

The Royal Society of London facilitated
the transition from politics to science in our branch
of the Cavendish family. Itself a legacy of the
scientific revolution, the Royal Society looked
upon scientific knowledge as public knowledge,
thereby opening up a new avenue of public service

"David Klliston Allen, The Naturalist in Britain: A Social History
(London: Allen Lane, 1976), 29.

""Boyle, Charles, Fourth Karl of Orrery," DNB 2:1017.

IJ A. Rupert Hall, "Oldenburg, Henry," DSK 10: 200-3, on 200.

"In reaction to the whiggish interpretation of the Glorious
Revolution, a recent generation of historians has given it a Cory bias,
emphasizing its conservative aspects. This trend is discussed in
Mark Goldic's review of Lois G. Schwoerer. The Declaration of Rights
1689 (Baltimore: The Johns Hopkins University Press, 1981), in
Parliamentary History, a Yearbook 2 (1983): 242-44.

l6 On this point, Joseph Priestley's lectures on History and General
Policy (London, 1826) are quoted and discussed in I. B. Cohen, " The
Kighteenth-Century Origins of the Concept of Scientific Revolution."
Journal of the History of Ideas 37 (1976): 257-88, on 263-64.

"Ibid, 264.

Cavendish

for the Cavendishes. The scientific lives of Lord
Charles and Henry Cavendish were public careers
and, moreover, careers built upon an idealism
worthy of those idealistic elements that did enter the
Glorious Revolution. The Royal Society, to which
the Cavendishes devoted themselves unstintingly,
upheld the Utopian dream of the scientific revo-
lution: scientific knowledge improves human life.

Since our subjects are eighteenth-century
men of science, and since we have made Newton's
Principia a prominent marker in this introduction,
we can envision the brickbats flying. For thirty
years now, historians of science have argued that
the eighteenth century should be regarded as a
time of originating scientific energies of its own
and recognized, as it was at the time, as another
century of scientific revolution. Historians have
reacted against the idolatry of Newton. w We
concede the point; nevertheless, in following the
tracks of our Cavendishes, we repeatedly confront
Newton. With Lord Charles Cavendish we are less
certain about this point than we are with his son.
Lord Charles was drawn mainly to instruments and
to their use in the new experimental fields, but his
early scientific associates were mathematically
accomplished colleagues of Newton. Lord Charles
entered the Royal Society the year Newton died.
I lenry Cavendish was educated at Cambridge at a
time when Newton's Principia dominated the
curriculum. Although his greatest contributions to
science were experimental, he was also a mathe-
matical scientist whose objective was to grasp the
new experimental fields in Newton's "mathematical
way." 1 '' New instruments, apparatus, and experi-
mental techniques were invented in the eighteenth
century', but not ev erything about science had to be
invented anew. The Principia was Henry Caven-
dish's luminous if ever-receding ideal; for his
purposes, it was still, after a century, science at its
best. It had introduced the mathematical physics of
forces, which made intelligible the world as an
orderly system; and the physics of forces was
Henry Cavendish's physics, as it still is the physics
of today. Cavendish incorporated a liv ing Newton,
not an icon. By the measure of his ambition.
Cavendish failed, but he did marvelous research in
the process. For the record, we do not subscribe to
the v iew (if it was ever held) that science of the
eighteenth century consisted in filling in the blanks
left by Newton's uncompleted natural philosophy.

In the accepted usage of his time, Henry
Cavendish was a "Newtonian philosopher," but to
call him that does little more than place him in the
eighteenth century. That ambiguity was implied by
the eminent mathematician Charles Hutton at the
close of the eighteenth century', in his Mathematical
and Philosophical Dictionary, where he identified
five meanings of "Newtonian philosophy," each
held by numbers of subscribers, to which we could
add several more meanings. We prefer to call
Cavendish a "natural philosopher"; namely, one
whose study of nature is founded on reason and
experience or, to draw again on Hutton's Dictionary,
one whose study of nature is characterized by an
"enlarged comprehension, by which analogies,
harmonies, and agreements are described in the
works of nature, and the particular effects
explained; that is, reduced to general rules."- 0

In one generation, roughly from the 16M()s
to the 1720s, science had come to dominate
educated thought in Western Furope. Science was
discussed in sermons, journals, coffee-house clubs,
and societies newly established for the purpose. 21
This was the time when Lord Charles Cavendish
was educated and introduced to politics and to
science. Not long after he was elected to
parliament, he was elected to the Royal Society,
and although he continued as an M.R for many years,
he was drawn to science. Cavendish was caught up in
the new currents of thought, which ultimately led
him to think of a new way of living, one that would
be continued by his son. Henry Cavendish would
find a completely fulfilling life within science.

In eighteenth-century Britain, people in
different stations of life attached their fortunes to
science in different ways. The Cavendishes' way

"*This by now historiograph ic commonplace once had some
freshness; eg.. R. W. Home. "Out of a Newtonian Straitjacket:
Alternative Approaches to Eighteenth-Century Physical Science." in
Studies in the Eighteenth Century. IV: Papers Presented ill the Fourth Davit/
Xichol Smith Memorial Seminar, Canberra 1976, eds. R. K Brissenden
and J. C. Kadc (Canberra: Australian National University Press,
1979), 235-49.

' 'New ton's expression, quoted and discussed in Henry Guerlac,
"Where the Statue Stood: Divergent Loyalties to Newton in the
Eighteenth Century," in Aspeefs of the Eighteenth Century, ed E. R.
Wasserman (Baltimore: The Johns Hopkins University Press, 1965),
317-34, on 323.

J "Kntries for "Newtonian Philosophy" and "Philosophy" in
Charles Hutton, Mathematical and Philosophical Dictionary, vol. 2
(London, 1795), 157 and 227.

-''Margaret C. Jacob, The Cultural Meaning of the Scientific
Revolution (Philadelphia: Temple University Press, 1988), 105.

Copyrighted maei

Problem of Cavendish

did not have long-term consequences, since in the
next century access to science became regular, as
science came to be organized in the manner of the
established professions. Indirectly, their way made
the point: for unlike the Cavendishes, persons
drawn to science were not rich aristocrats, and for
them to make a life in science, a new career had to
be invented. There did, of course, continue to be
the occasional wealthy scientific aristocrat, but
wealth and rank were then incidental, as they had
not been to the Cavendishes. The Cavendishes did
have direct consequences in science, but these
were based on Henry Cavendish's example as an
exacting experimental and mathematical in-
vestigator. When Cavendish died in 1810, a
distinguished French scientist wrote to a colleague
that Cavendish was a "model for those who
cultivate the physical sciences." 22 This "model"
was not of the occupant of the particular niche that
Charles and Henry Cavendish had made for
themselves in the society of scientific practitioners
but of the man of precision who had recently
weighed the world. Henry Cavendish contributed
to advances in experimental precision, a leading
development in the physical sciences in the second
half of the eighteenth century. His example of
technique carried over from the earlier setting of
scientific practice to the modern one.

Lord Charles and Henry Cavendish present their
biographers with a difficult problem. The
acquisitive habit of their family ensured that every
scrap of paper having to do with property was
saved for the record but that almost nothing else
was. We have Lord Charles Cavendish's business
correspondence, but his large private correspon-
dence is all gone. Henry Cavendish's business cor-
respondence is preserved too, but other than that,
for such a prominent man, his surviving cor-
respondence is meager in the extreme. To judge
from what we have seen, it would appear that he
never recorded a feeling or a thought about life. He
had a professional correspondence, which was
never large but which is invaluable to his
biographers, and a portion of this has survived.

Virginia Woolf approached her biography of
Roger Fry with the question, "How can one make
a life of six cardboard boxes full of tailors's bills,
love letters, and old picture postcards?" 23 The
answer is, as she went on to show, that it is not easy

but that it is not impossible either. Henry
Cavendish, whose cardboard boxes contain nothing
so personal as even tailors' bills, let alone love
letters, presents his biographers with an even
harder task. How can they make a life from a fifty-
year record of observations of thermometers and
magnetic needles? It is not easy or straightforward,
but once again, as we hope to show, it can be done.
Cavendish's scientific writings are revealing of his
individuality; in a way, they are his love letters.

When Cavendish died his scientific papers
passed to his principal heir, Lord Ceorge
Cavendish. They evidently remained with Lord
Ceorge's family until his grandson became the
seventh duke of Devonshire in 1858, at which time
they were removed to the ancestral house of the
Devonshires, Chatsworth, where they remain. 24
The papers, which consist of experimental and
observational data, calculations, and studies in
various stages of writing, are voluminous, an
embarrassment of riches which pose a biographical
hazard of their own. We have heeded Henry Adams's
advice to biographers, "proportion is everything," 25
while at the same time we have accepted that
Cavendish's life was his science. The distinction
between biography and history of science can be
fine, and in the case of Cavendish, we have had to
do a balancing act. This biography could not have
been written without Cavendish's unpublished
papers, and we have relied extensively on them. At
the same time we have tried not to lose a sense of
proportion and with it the man.

Some of Cavendish's manuscripts have
been published, though only one group of them,
the electrical, with anything approaching complete-
ness. His electrical papers were examined by a
series of experts in that branch of physics, first by
William Snow Harris, who borrowed them from the
earl of Burlington and included extracts from them

"Claude Louis Berthollct to Charles Blagden, 21 May 1810,
Blagdcn Letters, Royal Society. B138.

2i Quotcd in Susan Sheets-Pycnson, "New Directions for
Scientific Biography: The Case of Sir William Dawson." History of
Science 28 (1990): 399-410, on 399.

^Treasures from Chatsworth, The Devonshire Inheritance. A Loan
Exhibition from the Devonshire Collection, by Permission of the
Duke of Devonshire and the Trustees of the Chatsworth Settlement,
Organized and Circulated by the International Exhibitions
Foundation, 1979-1980, p. 67.

"Quoted in John A Oarraty, The Nature of Biography (New York:
Knopf, 1957), 247.

Cavendish

in a revision of his textbook on electricity. 26 In 1849
William Thomson visited William Snow Harris and
examined Cavendish's manuscripts.- 7 Thomson
thought that Cavendish's electrical manuscripts
should be published in their entirety, and he
together with several other men of science put the
case to the duke of Devonshire. In 1874 the duke
placed the manuscripts in the hands of the first
Cavendish Professor of Experimental Physics,
James Clerk Maxwell. For the next five years,
Maxwell repeated Cavendish's experiments,
transcribed the manuscripts, and prepared a
densely annotated and nearly complete edition of
Cavendish's unpublished electrical papers together
with his two published electrical papers. This
extraordinary edition was published by Cambridge
University Press only a few weeks before
Maxwell's death in 1879, as The Electrical Researches
of the Honourable Henry Cavendish. 1 * Cavendish's
unpublished chemical papers came to the attention
of chemists in the context of a resurrected priority
dispute over the discovery of the composition of
water. To document his defense of Cavendish's
claim, in 1839 Vernon Harcourt appended a
selection of Cavendish's chemical manuscripts to
his published presidential address to the British
Association for the Advancement of Science.
I larcourt believed that an edition of Cavendish's
papers was then being planned. 3 '' In fact, there had
been intermittent discussion of such a plan from
the time of Cavendish's death, but for one reason
or another it had been put off, as it would continue
to be long after Harcourt. In due course, with
further delays caused by World War I, in 1921
Cambridge University Press reprinted Maxwell's
edition of the electrical papers and published a
new, companion volume containing the rest of
Cavendish's published papers from the Philosophi-
cal Transactions along with a small selection of
scientific manuscripts from outside the field of
electricity, the two volumes appearing as The
Scientific Papers of the Honourable Henry Cavendish,
F.R.S. i0 The selection this time was made by the
general editor and chemist Edward Thorpe,
together with four other experts from physics,
astronomy, and geology.

The bulk of Cavendish's scientific-
manuscripts remain unpublished. We might
assume that every scrap of writing by Cavendish
about science has been preserved if we did not

have conclusive evidence to the contrary. A case in
point is the Cavendish experiment, his weighing of
the world: if as with so many of his researches, he
had not published it, we would know nothing of its
existence, as his scientific papers, as they have
come down to us, reveal no trace of it. Or to take an
example of another kind: Richard Kirwan, a
colleague of Cavendish, wrote to foreign scientist
that Cavendish had made a discovery about
magnetism that "merits great attention." 51 The
surviving manuscripts on magnetism by Cavendish,
which are primarily about earth-magnetic instru-
ments, give no hint of what this discovery might
have been. In recent years important new scientific
manuscripts of Cavendish have been made public,
and we have no doubt that many others once
existed and, we hope, may one day come to light.

As needed, we refer to the several
obituaries and brief early accounts of Cavendish, a
number of which were written by persons who
knew him. There are two book-length biographies
of Cavendish, both by chemists. The recent
biography by A. J. Berry 7 provides a readable
summary of Cavendish's papers but gives little
more than what the editors of the collected papers
do, and it does not present anything new about
Cavendish's life. 52 Berry would seem to have

26 William Snow Harris, Rudimentary Electricity, 4th ed. (London.
1 854). In the preface, he says that Lord Burlington has loaned him
Cavendish's manuscripts to use as he sees fit. He gives a fair sense of
the scope of Cavendish's electrical researches with the object of
showing how much of the modern subject Cavendish has
anticipated.

27 S. P. Thomson, The Life of William Thomson, Baron Kelvin of
Largs, 2 vols. (London, 1901) 1:218.

2 "The Electrical Researches of the Honourable Henry Cavendish, ER.S.,
ed. J. C. Maxwell (Cambridge, 1879; London: Frank Cass, 1967).

-"*W. Vernon Harcourt, "Address," British Association Report, 1839,
pp. 3—45, on p. 45. The address is followed by an "Appendix," pp.
45-68, containing extracts of Cavendish's papers on heat and
chemistry, which in turn is followed by sixty pages of lithographed
facsimiles of Cavendish's papers.

u '7he Scientific Papers of the Honourable Henry Cavendish, ER.S., 2
vols. (Cambridge: Cambridge ( diversity Press, 1921). The subtitle
of the first volume edited by Maxwell and revised by Joseph Larmor
is Electrical Researches. The subtitle of the second volume under E.
Thorpe's general editorship is Chemical and Dynamical. Hereafter, this
work is cited as Sci. Pap. 1 and 2.

"Richard Kirwan to Louis-Bernard Cuyton dc Morveau, 28 Feb
1786, in Louis-Bernard Cuyton de Morveau and Richard Kirwan, A
.Scientific Correspondence During the Chemical Revolution: Louis-Bernard
Cuyton de Morveau and Richard Kirwan, 11X2-1802, ed. E. Orison, M.
Sadoun-Coupil, and P. Bret (Berkeley: Office for the History of
Science and Technology, University of California at Berkeley, 1994),
142-47, on 146.

32 A. J. Berry, Henry Cavendish: His Life and Scientific Wort
(London: Hutchinson, 1960).

Problem of Cavendish

confirmed what the editor-in-chief of the collected
papers, Thorpe, said: Little is known about the
"personal history" of Cavendish, "nor is there
much hope now that more may be gleaned," since
it is doubtful that "there is much more to learn" about
this "singularly uneventful" life." Cavendish's
earlier biographer, Ceorge Wilson, however, wrote
an original account of his subject in a highly
unusual form of biography. 34

If ever a biography violated Adams's adv ice
about proportion, it was Wilson's The Life of the
Honourable Henry Cavendish. Cavendish's "life," in
the ordinary sense of the word, occupies only two
chapters, the first and the fourth, which comprise
fifty pages out of a total of nearly five hundred
pages. The "life" in the Life was stuck onto a book
with a different purpose; namely, to put to rest the
priority dispute that had prompted Harcourt's
intervention. The dispute, which had simmered
briefly in Cavendish's lifetime, was fanned to white
heat in the middle of the nineteenth century by a
French eloge of James Watt, which advanced
Watt's claims over Cavendish's. Dealing almost
exclusively with the water controversy, Wilson's
account has elements of a detective story and legal
drama; his principal subject was, after all, not
Cavendish but a fight for prize and honor. Apart
from the polemics, the book is a useful work in the
history of chemistry, though it does not seem to
have been used that way. What it has been used for
is the "life" of Cavendish, little longer than some
of the character sketches it drew on.

Wilson's biography was published by and at
the request of the Cavendish Society. Founded in
1846, the Society was one of a number of early
nineteenth-century subscription printing clubs,
this one for chemical works and named after Henry
Cavendish no doubt because of the furor going on
then. 35 In addition to the water controversy and the
subscription printing club, there was one other
reason for Wilson's Life. In the middle of the
nineteenth century, a call went out for biographies
of scientists, presumed to be a neglected category
of eminent Britons. Believing that scientists and
men of letters gave their age "greater glory than
the statesmen and warriors," 3 ' 1 in 1845 Lord
Brougham published biographical sketches of
Cavendish and several other scientists. In 1848 the
historian of the Royal Society Charles Richard
Weld condemned the lack of a biography of the

late president of the Society Joseph Banks as a
"reproach to scientific England." If Banks had
been a military man or a romantic hero, his biog-
raphy would long since have been written, Weld
said. 37 In 1843 Wilson began collecting materials
for a book on the lives of the British chemists. He
never did publish this book, but in the life of the
chemist he did publish, Cavendish's, in 1851, he
regretted that "no other European nation has so
imperfect a series of biographies of her philoso-
phers, as Britain possesses." There was not even a
good biography of Newton, Wilson said, let alone
biographies of Thomas Young, William Hyde
Wollaston, and John Dalton, and only now was
there a biography of Cavendish.™ That Wilson
included a "life" at all in his book on Cavendish
was due to his sympathy with the general desire for
biographies of scientists.

When Wilson applied to the Cavendish
family for the loan of Henry Cavendish's manu-
scripts, he said he had delayed asking because he
understood that Lord Burlington was going to write
an account of Cavendish's discoveries. (We start
here with esoterica about British titles: the earl of
Burlington, an extinct title, was resurrected by
William IV as a courtesy title for Henry Caven-
dish's heir, Lord George Cavendish; thereafter it
went to the eldest son of the eldest son of the duke
of Devonshire.) This Lord Burlington was the
forty-eight-year-old William Cavendish, who would
go on to become the seventh duke of Devonshire.
A scientifically gifted man who placed second
wrangler in the competitive mathematical exami-
nations at Cambridge and first Smith's Prizeman,
the duke returned to Cambridge in 1861 to suc-
ceed Prince Albert as chancellor. The richest of all
the dukes, in 1870 he drew on his wealth to build a
laboratory for experimental physics at Cambridge
(where its first professor, Maxwell, would repeat
Cavendish's experiments for his edition of Caven-
dish's electrical papers). The laboratory was going

"From Thorpe's "Introduction" to Cavendish, Sci. I'ap. 2:1.
M George Wilson, The Life of the Honourable Henry Cavendish
(London, 1851).

35 W. H. Brock, "The Society for the Perpetuation of Gmelin:
the Cavendish Society, 1846-1872," Annals of Srienre 35 (1978):
599-617, on 604-5.

"•Brougham, Lives of Men of Letters and Srienre l:xi.

"Charles Richard Weld. A History of the Royal Society, .... 2 vols.
(London, 1848) 2:116-17.

'"Wilson, Cavendish, 15.

Cavendish

to be called the Devonshire Physical Laboratory
after the seventh duke, but it was named the
Cavendish Laboratory instead, after Henry
Cavendish. 39 The seventh duke did not write an
in-house biography after all, but he established one
of the world's greatest physical laboratories and saw
to it that it was named after the greatest representa-
tive of his family, Henry Cavendish. Wilson told the
future duke that he had been studying Cavendish's
works for ten years, that he admired Cavendish's
character, and that he intended to do him justice in
the water controversy. 40 Burlington let Wilson see
the manuscripts.

Wilson drew his conclusions about Cavendish
largely from stories he collected, many of them
from old timers at the Royal Society and former
neighbors of Cavendish. The stories conflict and
often contain things that could not be true, yet
taken together they are suggestive. Like the
hundreds of unverifiable stories about Lincoln,
they are most revealing of the time in which they
were told, but they also tell something about the
man. 41 The stories illustrate two rather forbidding
traits of Cavendish, a pathological fear of strangers
that could render him speechless, and a clockwork
regularity in all his transactions with life. W'ilson
tried to understand his man: he tried to "become
for the time Cavendish, and think as he thought,
and do as he did." But as he closed on his subject,
Wilson conflated Cavendish with the remorse he
felt on devoting so much time and effort to "so
small a matter." Like all his past efforts, this effort
Wilson saw as "bleak and dark," and the image of
the man he distilled from the Cavendish stories
corresponds. 4 -

Wilson kept his promise to Burlington to
portray Cavendish as a man of exemplary probity.
But there is more to character than honesty, and
Wilson did not admire the rest of what he saw. A
deeply religious man, Wilson at the time he wrote
his life of Cavendish was contemplating writing a
"Religio Chemici" along the lines of Sir Thomas
Browne's "Religo Medici," and in the year
following the publication of his life, he published a
biography of the physician John Reid, a man of
"Courage, Hope, and Faith," whom he greatly
admired. Wilson tried to penetrate to where
Cavendish's courage, hope, and faith lay, his heart,
only to discover that Cavendish was a "man without
a heart." 4 ' In the Life, Wilson said that Cavendish

was "passionless," "only a cold, clear Intelligence,
raying down pure white light, which brightened
everything on which it fell, but warmed nothing."
Wilson's striking judgment has been uncritically
repeated. Francis Bickley, chronicler of the
Cavendish family, concluded from Wilson's Life
that "there is something pathetic about such an
existence as Henry Cavendish's, so fruitful and yet
so utterly barren." 44 Edward Thorpe, general editor
of Cavendish's Scientific Papers, wrote to a fellow
editor that Cavendish was "not a man as other men
are, but simply the personification and embodiment
of a cold, unimpassioned intellectuality." 45 Caven-
dish's recent biographer, A. J. Bern,', quoting Wilson,
speaks of Cavendish's "striking deficiencies as a
human being." 4 '' Wilson is entitled to his image of
Cavendish, but we should point out that in addi-
tion to being his conviction, it is a mid nineteenth-
century Romantic cliche. It is Keats's Appolonius,
whose cold mathematical philosophy denies the
imagination by subjecting the rainbow and all other
mysteries to its "rule and line," emptying them of
charm by conquering them. We have dwelled this
long on Wilson's biography because it has provided
the portrait of Cavendish for nearly a hundred and
fifty years. We have consulted a much wider range
of sources than Wilson did, and so our account
naturally shows differences from the original. And
times have changed and biographies with them.

We can, it would seem, at least agree on the
appearance of Henry Cavendish, since there is only
one portrait. The original was a graphite and gray-
wash sketch, from which Wilson had an engraving
made for his biography. Cavendish was an im-
mensely wealthy man, but one would not know it
from this portrait, which shows him in his rumpled
coat and long wig, both long out of date, and with

w John Pearson, The .Serpen/ and the Stag: The Saga of England's
Powerful and Clamourous Cavendish Family from the Age of Henry
the Eighth to the Present (New York: Holt. Rinchart and Winston,
1983), 214.

4 "(ieorge Wilson to Lord Burlington. IS Mar 1850, Lancashire
Record Office, Miscellaneous Letters, DDCA 22/19/5.
4l Garraty. Biography, 216-17.

42 The quotations are from a letter Wilson wrote at the time,
included in his sister's biography, Jessie Aitken Wilson, Memoir of
George Wilson (London, 1H62), 340—41.

•"Ibid.. 338, 342-43.

♦•Francis Bickley, the Cavendish Family (London: Constable,
1911), 207.

4S Kdward Thorpe to Joseph Larmor, 7 Feb. 1920, Larmor
Papers. Royal Society Library, 1972.
*'Bcrry, Cavendish, 22.

Problem o f Cavendish

his slouching walk. The latter was a family trait: of
the Cavendishes, Horace Walpole observed that a
"peculiar awkwardness of gait is universally seen in
them." 47 The physical scientist Thomas Young,
who knew Cavendish in his late years, said that he
always dressed the same way, presumably as in this
picture. 48 (Young also described Cavendish as tall
and thin, which is where agreement ends; another
contemporary, the chemist Thomas Thomson,
described Cavendish as "rather thick" and his neck
as "rather short." 44 ) The circumstances under
which this picture was executed make one of the
best stories about Cavendish, and one there is no
reason to doubt. Whenever he was approached to
sit for a portrait (probably for the meeting room of
the Royal Society), Cavendish always gave a blunt
refusal. But William Alexander, a draughtsman
from the China embassy, succeeded by subterfuge;
with the help of an accomplice, John Burrow, he
was invited as a guest to the Royal Society Club, at
which Cavendish dined once a week. As advised,
Alexander sat at one end of the table close to the
peg on which Cavendish invariably hung his green
coat and three-cornered hat, both of which he
surreptitiously sketched. He then sketched
Cavendish's profile, which he inserted between the
hat and coat at home where he finished the
portrait. Cavendish, of course, was not shown it,
but people who knew him were, and they
recognized it as Cavendish. The artist left the
sketch at the British Museum, where Wilson
obtained it. 50 It is a wonderful sketch, and part of
the wonder is that it ever came into existence in
the first place.

"I desire" was one of Cavendish's favorite
expressions. His life was filled with desire, and to a
greater extent than most persons, what he desired
he could have. For he was perfectly placed: born an
aristocrat when the aristocracy was in high tide, he
could expect his desires to be taken seriously. Be-
cause he was not a peer, he escaped the meaningless
aspects of privilege, the time-consuming duties,
rituals, and display; he was free to choose in-
herently more rewarding pursuits, while at the
same time he could feel as confident of his place in
society as the duke of Devonshire. (As far as his
place was concerned, Henry Cavendish had
absolute confidence; his lack of confidence in
particular social groups was an entirely different
matter.) What he desired more than anything else,

we know, was to understand the natural world.
Given his enviable position, he could separate the
rewards of scientific work from those of society at
large, which were in any event given to him
without having to desire them. That advantage
lent his life its peculiar direction and intensity.

Owing to the nearly total absence of
biographical materials of a personal sort, we have
had to rely upon other kinds of evidence. To get to
know Cavendish and form our image of him, to
draw the human face between the three-cornered
hat and the crumpled great-coat, we have placed
him in all the human settings in which we know he
appeared. The result is a long book. Critical readers
will say that Cavendish is again unfortunate in his
biographers, who do not know when to stop.
Sympathetic readers will see our predicament and
consider our worst fault to be the common lot of
biographers, an overenthusiasm for their subject.
We have handled the Cavendish "problem" in the
way a sculptor works with a resistant material like
stone. To give form to it, the sculptor is condemned
to work constantly from the outside inward. No
matter how much material he works, the visible
product of his labors is never anything but an outer
surface, though the viewer may think of the
sculpture as being solid as well. This analogy gives
us a little courage, but it does not go very far; the
sculptor's intention is art, and the form we have
given this biography is intentionally artless (in one
of its meanings).

The period we consider in this biography
covers just over a century, from the end of the
seventeenth century to the beginning of the
nineteenth. It was an extraordinary 1 time in science,
when great new fields of investigation were laid
down. Lord Charles Cavendish, a master of
scientific instruments and experimental art, took
up challenging problems in these fields, and his son
Henry Cavendish explored them systematically
with exacting experimental technique and mathe-
matical theory'. The time of Lord Charles and

47 Horacc Walpole to Horace Mann, 4 June 1749. in Horace
Walpole's (correspondence, eel. W. S. Lewis et al., 48 vols. (New Haven:
Yale University Press, 1937-83) :15:317.

•Thomas Young, "Life of Cavendish," Encyclopaedia Britannica,
Supplement, 1816-24: in Cavendish, Sri. Pap. 1:435—47, on 444.

^Thomson, The History of Chemistry 1:339. s "John Burrow, Sketches
of the Royal Society and Royal Society Club ( I xmdon, 1 849), 1 46-47.

s "John Burrow, Sketches of the Royal Scoiety and Royal Society Club
(London, 1849), 146-147.

C.ci-cendkli

Henry Cavendish was (as all times are) one of
transition, in this instanee from the passing era of
the scientific "virtuosi" to the dawn of our own era
of scientific professionals. In terms of the
Cavendish family, the period begins when the
rooms of the great Cavendish house, Chatsworth,
resounded with the pugnacious first duke of
Devonshire's clanking sword, and it ends when the
tone of those same rooms was set by the Proustian
languor of the fifth duke of Devonshire. Where the
first duke saw worlds to conquer, the fifth duke
saw only the already conquered world in which his
comfort was well secured. The fifth duke was no
fool. He saw that his cousin Henry Cavendish
existed in another world, though he may not have
recognized it as a new world to conquer, one which
demanded of Henry what had been demanded of

the first duke, hard work. (By "conquer," in the
borrowed sense, we mean to understand the
workings of nature, ruled by the authority of
natural laws.) The fifth duke got it nearly right
when he ordered his wife Ceorgiana, duchess of
Devonshire to stay away from Henry Cavendish
(she did not obey) on the grounds that "He is not a
gentleman — he worfo." 51 In this biography, we show
what it meant for two gentlemen, first, Lord
Charles Cavendish and, then, Henry Cavendish to
work in science. 52

5, Bicklcy, Cavendish Family. 202

5Z Wbrt in the setting of professional science is our theme in
Christa Jungnickel and Russell McCormmach, Intellectual Mastery of
Nature: Theoretical Physics from Ohm to Einstein, 2 vols (Chicago:
University of Chicago Press. 1986).

Copy nghled material

PART 1

The Dukes

PART I

The Dukes

Jn the spring of 1691, two young English aristocrats
on the grand tour on the Continent met in Venice
and apparently liked one another well enough to
begin a correspondence after they parted. 1 The
older of the two was Henry de Grey, Lord
Ruthven, then not quite twenty, the younger the
nineteen-year-old William, Lord Cavendish. Forty
years later, in 1731, they were to become the
grandfathers of Henry Cavendish, although William
did not live long enough to know of this grandson.

The eldest sons of propertied English earls,
the two young men, accompanied by tutors and
servants, met as seasoned travelers despite their
youth. William Cavendish had already been abroad
for over two years, Henry de Grey for over a year. 2
William was on his way to Rome, Henry returning
from there. Both of them were no doubt acquiring
the rudiments of their later great interest in the arts
and architecture, but letters about their travels do
not show any youthful ardor for the beauties of
Italy, Switzerland, or The Netherlands. In Rome,
William Cavendish and his younger brother Henry
did "little or nothing . . . that was worth giving your
Lordship an account of." 3 From Padua, Frankfurt,
or The Hague they reported seeing friends or
missing them, as they crisscrossed the Continent,
but not a word about the finer things of classical
civilization these young English barbarians had
been sent abroad to experience.

What did interest them was the war
threatening between England and its allies and
France and the dynastic quarrels that were giving
rise to it. The war might affect their travel plans, as
it did Henry de Grey's, but, more important, it was
to be fought to secure the rights to power and
property of certain European ruling families, the
usual purpose of wars then, and understandably a
matter of concern to aristocrats of high rank like
young Cavendish and Grey.

The Elector of Brandenburg has declared, that he
will fullfill the Promise he made to the Duke of
Lorrain, at the siege of Bonn, to maintain the

interests of his children and to contribute to their
restoration. The Emperor and all the allys have
declared the same thing,
William Cavendish reported to Henry de Grey in
the summer of 1691 . 4 The concern for the dynastic
interests of the ruling family that an aristocrat
chose to ally himself with was very much a concern
for the interests of his own family. That was why
William Cavendish was ready to risk his life in
battle in 1691 and why his father, the earl of
Devonshire had risked his life only three years
earlier to secure the interests in England of the
Protestant branch of the Stuarts.

In 1688, William Cavendish's father, the
earl of Devonshire, had joined six other English
aristocrats in the risky business of inviting William
of Orange to the British throne, even though that
throne was then rightfully occupied by James II
and could some day be legally claimed by James's
son, who had just been born. If their scheme of
deposing James had misfired, they might have
suffered the fate of traitors. But luck was with
them, and with the succession of William and his
Stuart wife, Mary, to the crown, the earl ensured
abundantly the survival of the Cavendish family in
political power and in the enjoyment of their
property. In 1691, in the spring of which William

'William Cavendish to Henry de Grey, 30 May/9 June 1691 and
23 December 1691 Bedfordshire Record Office, Wrest Park
Collection, L 30/8/14/1-2.

-One of William Cavendish's first stops on the Continent was at
Brussels, from where he wrote to his mother-in-law. Lady Russell. He-
was about to continue on his tour, and she approved, "for to live well
in the world; 'tis for certain most necessary to know the world well."
letters of Lady Rachel Russell: from the Manuscript in the Library til
Woburn Abbey, 5th ed. (London, 1793), 415-16. Henry de Grey, as
Lord Ruthven, had been issued a pass on 16 April 1690 "to travel
abroad for purposes of study." G. E. C. (George Edward Cokayne),
The Complete Peerage of England Scotland Ireland Great Britain and the
United Kingdom: Extant, Extinct, or Dormant, vol. (3) (Gloucester Alan
Sutton. 1982), 176-78. The Cavendish and Grey families were
connected through marriage, in 1601. Ibid., 173-74.

'Henry Cavendish to Henry de Grey, 7/19 May 1691, Bedford
County Record Office. Wrest Park Collection. L 30/8/21/1.

■•William Cavendish to Henry de Grey, 30 May/9 June 1691.
Bedfordshire Record Office, Wrest Park Collection, L 30/8/14/1.

Cavendish

and Henry met in Venice, the earl of Devonshire
outshone "most of the Princes," including the
elector of Brandenburg, with his "magnificent"
establishment at the royal congress at The Hague,
to which he had accompanied King William as lord
steward. Three years later, in 1694, the royal couple
rewarded his services by raising the earl to duke of
Devonshire, the highest rank short of royalty. 5

Traditionally the number of dukes in the
land was extremely small, one or two. That
changed during the Restoration with Charles I Is
spate of peer-making, especially of dukedoms,
which he gave to his mistresses and six bastard
children. At the beginning of the eighteenth
century there were about 160 English peers and
among them about 20 dukes, figures which
remained pretty constant thereafter into the
twentieth century. After acquiring the throne,
between 1688 and 1694 the new king, William III,
created a group of new noble titles including seven
dukedoms,'' and Devonshire had profited from this
brief, post- Revolution beneficence.

The Cavendishes rose to their title
relatively quickly, in not much more than a century,
and they prepared for it by a steady accumulation
of landed property until they were among the
richest landowners in Kngland. Along the way, they
used some of their money to buy first a baronetcy
and then an earldom when the political shifts of
the seventeenth century from monarchy to
commonwealth and back to monarchy prompted
the granting of royal favors. They remained loyal to
the Stuarts — being prudent enough to make their
peace with the commonwealth as well — until
under Charles II such loyalty was no longer in their
financial and political interest. 7

If the dynastic concern of the Cavendishes
was to further strengthen their newly found hold
on the top rung of the social ladder, the Greys' was
to reclaim their former footing. The Greys had been
earls of Kent since the fifteenth century, Henry de
Grey's father the eleventh of the line. But Henry's
branch of the family had succeeded to the title and
estates only in the middle of the seventeenth
century, beginning with a country rector with a
very large family who was too poor and too old to
take his seat in the House of Lords. His successor,
Henry's grandfather, did enter politics, but on the
wrong side, as it turned out, adopting the cause of
parliament against the king. After the restoration of

the Stuarts, the Greys prudently kept their
distance from court and parliament. In any case,
their most pressing need was still to secure their
estate and finances; at court or in government in
those troubled years, they would only have risked
making enemies or spending money that they
could not afford. Taking big chances, as the earl of
Devonshire had on behalf of William of Orange,
was acceptable to a prudent man only if he had
power, and power then derived from landed
property. In that regard, the Greys were not the
Cavendishes' betters or even equals. Nor would
they take chances with the life of their heir.
Instructing Henry to leave Holland before the king
arrived there for his campaign, Henry's father
wrote to him: "It would be expected you should go
to the campaign with him, and not to do it would
be took ill both from your father and you." So
Henry traveled on to Geneva, and from there,
against his cautious parents' wishes, into Italy. 8

Persona! Characteristics

If Henry had any brothers, they died young,
for soon the love and hope of his family focused on
him. He responded by developing into an af-
fectionate young man, good natured, easygoing.
Once he had a family of his own, his concern for his
wives — after his first wife died, he remarried — and
his children was reflected in their letters to him,
full of warmth and appreciation. He was not espe-
cially gifted in anything, but he had sufficient
intelligence and curiosity to inform himself on a
wide range of subjects, including science, as his
substantial library attests. One of his contemporaries
in 1707 credited him with "good sense" and with
always being "very moderate.'"' Be that as it may,
he had dynastic ambitions for his family and
enough vanity to aspire to important positions at
court, only he lacked the drive to work for such

"■John Pearson. The Serpen! and the Stag: The Saga of England's
Powerful anil Glamourous Cavendish Family from Age of Henry the Eighth
to the Present (New York: Holt, Reinhart & Winston, 1983), 68-71
Francis Bickley, The Cavendish Family (London: Constable, 1911),
170-74.

'•J. V. Beckett, The Aristocracy in England, 1660-1914 (Oxford:
Basil Blackwell, 1986). 27-28.

"Pearson. Serpent and Stag, 61.

"Joyce Godber, Wrest Path and the Duke oj Kent, Henry Grey
11611-1740), 4th ed. (Elstow Moot Hall: Bedfordshire County
Council Arts and Recreation Department. 1982), 2-3.

''(i. E. ( :.. the Complete Peerage 3( 7 ): 1 78.

The Dukes

positions by seeking political power. "A quiet mind
is better than to embroil myself amongst the
knaves and fools about either Church or State," he
wrote at a moment of disappointment. 10 He sought
offices in the courtier's way, through gaining favor
with influential people and then using his
connections to request honors and positions. The
offices he accepted were administrative rather than
political, requiring abilities well within his reach
and skills he was already exercising in the running
of his estates. He attended the House of Lords
dutifully even when he came to dislike the burden
in his middle years." He displayed the same level-
headed estimate of his abilities in his later years,
when his chief occupation came to be his estate at
Wrest Park, its agriculture and its gardens,
informing himself thoroughly on those subjects
and planning and directing the work with
considerable and lasting success. His enemies at
court — political opponents who wanted the
positions he held, or rivals for royal favors — gave
Henry de Grey the name "The Bugg"; 12 they meant
to ridicule him, implying in this way that he was
pompous and proud, but their description must be
admitted to have some truth to it. A good-looking
man, he spent the money necessary to cut a fine
figure, his annual clothes bills running higher than
those of his wife and several daughters combined,
not only while he held high office at court and
needed expensive formal apparel, but long before,
as a young man about town. On his tomb, he had
himself sculpted wearing a Roman toga over a
strong, muscular body, his curly hair cropped close
to the head, resembling in face and attire Laurent
Delvaux's statue of George I, undeniably betraying
a certain vanity. A large family portrait painted
about five years before his death shows him to be,
on the contrary, a relatively short, slender man
whose simple velvet coat is decorated only with
what appears to be the garter and ribbon. Far from
posing as the patriarch in his own home, he has
yielded center stage to his mother-in-law, the
countess of Portland, who was governess of the
royal children; he stands rather meekly by her side,
receiving from her a cup of tea." His pride lay in his
"ancient and noble" family, as he called it, which
he hoped, in vain, as it turned out, to continue
through his five sons. Not one of them survived
him. 14 He achieved a dukedom for his family in
1710, but he ended up without an heir to inherit it;

he could only look forward to its extinction with his
death. All that remained for him to do was to build
an ostentatious marble mausoleum, which although
pompous, also evokes his struggle against so much
disappointed hope.

For at least ten years, beginning in 1736, the Kent
estate served as a lecture theater in the physical
sciences and an observatory. In those years the
duke of Kent and, after his death in 1740, the
duchess of Kent employed Thomas Wright as a
scientific teacher. This is the famous astronomer
who was first to delineate the structure of the
Milky Way, which he published in 1750, as An
Original Theory or New Hypothesis of the Universe.
Born into an artisan family, self-taught in astrono-
my, Wright made his living by teaching science,
mathematics, and surveying, publishing on these
subjects, and surveying the estates of the aristoc-
racy. His pupils included Jemima, duchess of Kent
and Kent's daughters Ladies Sophia de Grey and
Mary de Grey (but not Lady Anne de Grey, who
married Lord Charles Cavendish), his son-in-law
Lord Glenorchy, and his granddaughter Jemima,
the future Marchioness de Grey. He taught the
Kent women geometry, navigation, surveying, and
no doubt other subjects from his ambitious cur-
riculum. Residing for months at a time at Wrest
Park, Wright probably did surveying there as well
as teaching, for the duke was always building, and
the duchess, Wright noted in his diary, surveyed all
the garden and made plans for it. Wright also
carried out his own astronomical studies at Wrest,
in 1736, for example, communicating to the Royal
Society from there his observations of the eclipse

l0 Duke of Kent to Prior, 26 July 1710, quoted in Ragnhild
Hatton. George I, Elector and King (Cambridge. Mass: Harvard
University Press, 1978), 121.

""Memoir of the Family of De Grey." Bedfordshire Record
Office. Wrest Park Collection, L 31/1 14/22,2.1. vol. 2. p. 99.

ir Fhe earl of Godolphin to the duchess of Marlborough, /24 Apr.
1704/, The Marlhotough-Godolphin Correspondence, 3 vols., ed. H. L.
Snyder, vol. 1 (Oxford: Clarendon Press, 1975). 284.

^Conversation Piece tit Wrest, around 1735. Illustration opposite p.
40 in Joyce Godber. The Marchioness Grey of Wrest Park, vol. 47
(Bedfordshire Historical Record Society, 1968).

I4 G. K. O, Complete Peerage 3:(7 '):47.

"What is known of Thomas Wright's life is based mainly on his
journal. Entries telling of his contacts with the Kent family arc
reproduced in Kdward Hughes, "The Early Journal of Thomas
Wright of Durham," Annals of Science 7 (1951): 1-24, on 13-22. His
observations at Wrest Park are reported in Royal Society. JB 15:371
(28 Oct. 1736).

Cavendish

of Mars by the moon. 15 Lord Charles and Henry
Cavendish may well have got acquainted with
Thomas Wright at Wrest Park with his telescope or
in London on tutorial visits to the Grey side of the
family. Wright was still teaching the Kents when
I Icnry Cavendish was fifteen.

An even more fitting monument to the duke of
Kent than the family vault at Flitton is Wrest Park
in Bedfordshire, with its vast and elegant garden,
one hundred and twenty acres bounded by a two-
mile gravel walk. Here and there inside the garden
the duke set out mementos of friends and of
princes he had served or admired, which included
statues of King William (put up because the duke
was a "good Whig") and of Queen Anne (put up
because he was a "good Servant"). Standing in a
corner of the garden was a pyramid inscribed with
the years of the beginning and end of the duke's
proud improvements. The larger setting, the park,
was eight hundred acres with a grass walk around
it, with exotic plantations, oak woods, canals
containing carp and pike, an obelisk eighty-six feet
high, extensive lawns, a pavilion, a greenhouse, a
bowling green, statues, vases, a temple of Diana,
falls, and herds of deer. In the distance cottages
and churches could be seen, including a church
that resembled a ruined castle. The grand house of
the estate was approached by a straight, broad,
mile-long, tree-flanked avenue. This description is
from a letter written at Wrest Park three years after
the duke's death, in 1743, by Thomas Birch. A
literary man, Birch thought that the best room in
the house was the library. We reflect that the legacy
of this combination of grandeur and learning
included the man of science Henry Cavendish.

Growing up in the shadow of the "Great Duke of
Devon" — his contemporaries spoke of the first
duke of Devonshire as if he were already a
legend — Henry Cavendish's other grandfather,
William Cavendish, the future second duke of
Devonshire, could have been crushed completely.
[Lis father was a willful, flamboyant man who
defied and created kings, picked violent quarrels at
the drop of a hat,"' and built one of England's
finest great houses, Chatsworth. In the event, the
son grew up to be more mature, better balanced,
more reasonable, and on the whole a much more
solid and, one suspects, more intelligent man than

the father — and, of course, a much less exciting
man. About William there are none of the stories
about duels and mistresses, street fights and
defiance of all authority that make the first duke
such fascinating reading. Up to a point, William,
reasonably enough, allowed his life to be directed
by his father: at sixteen, he was married to
fourteen-year-old Rachel Russell, the daughter of
Lord William Russell, Devonshire's former political
ally and friend and now "martyr" to the whig
cause. 17 As soon as William came of age, he
followed his father into politics. In his early years
as a member of parliament, he even imitated his
father's boldness, taking initiatives and speaking
frequently for his principles in the House of
Commons, on one occasion going so far as to
challenge an opponent. But when he spoke up, he
spoke his own mind, not his father's, and to tackle
conflicts, he was much more likely to use
reasoning, persuasion, and compromise than the
sword. "His mansion was not a rendezvous for the
assemblies of foppery," it was said of him: "none
were permitted to partake of the . . . refined . . .
pleasures of his house . . . but the ingenious, the
learned, the sober, the wise." 18 He was not really
that proper, but he did value learning and cool
judgment, and in an environment of courtly
intrigue and political passions, he impressed the
duke of Marlborough as a "very honest man" and a
man w ho "governs himself by reason." 19 George I,
according to Lady Cowper, thought so, too: he was
one of only two men in the kingdom whom the
king had found "very honest, disinterested" men. 20
Of his relationship with his family we get a
glimpse only now and then. As a newly married
boy, too young yet to be allowed to live with his
wife, on his continental tour, he wrote considerate
letters to his mother-in-law. Lady Rachel Russell,

l6 Greac Britain. Historical Manuscripts Commission, Report on
the Manuscripts o f the Marquess of Downshire, Preserved at Easthampstead
Pari. BertsVol. 1: Papers of Sir William Trumbull. Part 1 (London: His
Majesty's Stationary Office, 1924). 60, 240, 268-69, 271-72, 276.

"Lois (;. Schwoerer, Lady Rachel Russell: "One of the Best of Women"
(Baltimore: The Johns Hopkins University Press. 1988), 161-63.

18 From Hiram Bingham, Elihu Yale: The American Nabob of Queen
Square (New York: Dodd, Mead, 1939), 308.

"The duke of Marlborough to the earl of (iodolphin, 14/25 June
1 708, in Marlhorough-Codolphin Correspondence 2:101 1.

^George 1 quoted by Lady Cowper, 10 July 1716, in Mary,
Countess Cowper, Diary of Man Countess Cowper. Lady of the
Bedchamber lo the Princess of Wales. 1114-1720, cd. C. S. Cowper
(London, 1864), U.S.

Copyrighted m aerial

7 "he Dukes

to which she replied: "I can have no better content
in this world than to have your Lordship confirm
my hope that you are pleased with your so near
relation to us here, that you believe us kind to you,
and value our being so."- 1 The boy's thoughtfulness
and good breeding made his high expectations all
the more agreeable. Writing about William and
Rachel's marriage, Lady Russell sensibly remarked:
"We have all the promising hopes that are (I think)
to be had: of those I reckon riches the least, though
that ingredient is good if we use it rightly." 22
William and Rachel Cavendish used their riches
responsibly and tried to teach their children to do
the same. Rachel apparently was the one to deal
with the children. "I must needs tel you y c y r father
can by noe means allow you to goe on in this way,"
she admonished their second son James for
gambling while on tour abroad, "& soe he bids me
tel you, y c expences of y r travels have been very
great already without y addition, more I believe
then is allow'd to most elder brothers, 6k tho I hope
y r father is able to make you very easy in y r
fortunes yet you may consider y° more you spend
aboard soe much y c less you will have at home
whare it wou'd doe you more credit & I should
think be more for y r owne satisfaction to spend y r
money amongst y r friends then strangers." 25 Lord
James never learned the value of careful husbandry
of his means, but, as we shall see, his younger
brother Lord Charles, accompanying him on this
trip, learned it very well. Like many of his well-to-
do contemporaries, William, duke of Devonshire
did spend some of his fortune on works of art;
however, even as a collector he managed to enrich
the family fortune. Whether out of frugality or
good taste, he avoided the more expensive but
often second-rate large works and instead acquired
one of the finest collections of old master drawings,
including works by Raphael, Diirer, Holbein,
Rubens, Van Dyck, and, above all, Rembrandt.- 4

William's reliance on reason and integrity, a
quality apparently shared by his wife, also is
reflected in their family life. "I have always taken
you to have a very good understanding," Rachel
wrote to James; "if you make but a right use of
that, you will know what is most for y r owne
good." 25 They encouraged their children to think
for themselves. In the matter of an allowance, for
example, Rachel twice asked James what he might
need while he was abroad, his parents reserving the

right to disagree with him: "I thought I was right to
aske y r opinion as to y c sum, concluding I knew
you soe well y c if I shou'd happen to think it too
much, you wou'd not take it ill y< I told you soe." 26
Their difference of opinion resulted in a com-
promise, with James sending pleasing reports of his
economy to his parents. With regard to the boys'
travels, too, "y r father in that wo'd be willing to do
what he thought was most agreeable to y r own
inclinations . . . you may let me know what y r own
thoughts are." 27 In a future son-in-law, William and
Rachel valued that he was said to be "very sober &
of an extreem good character w th is above every
thing elce." 2x This sensible family life not only
nurtured love and respect but also the clear thinking
and the level-headed assumption of responsibility
of Lord Charles Cavendish.

Career of the Duke of Devonshire

From the time he returned from his
continental tour until his death in 1729, William
Cavendish, from 1707 the second duke of
Devonshire, continuously devoted much of his life
to public service at the highest level of govern-
ment. 2 '' This is not the place to discuss all the
details of his public life, but some aspects of it are
indispensable to our understanding of his son Lord
Charles and his grandson Henry Cavendish. First,
his public position determined theirs", for both of
them, and for all those with whom they came into
contact, their being a Cavendish was no small matter.
Second, the nature of his public life reveals much
about his understanding of his public role and
obligations. Whether in politics or in science, Lord

-'Lady Russell to William, Lord Cavendish. 5 Oct. 16XK. in
Letters of I. nth Rachel Russell, 410.

"Lady Rachel Russell to Dr. Fitzwilliam, 29 June 168K. Letters
of Lady Rachel Russell, 399.

-'Rachel, duchess of Devonshire to Lord James Cavendish, /late
1722 or early 172.V, Dcvon.Coll.

'■•John Pearson, Serpent and Stag, X7-HH.

-'Rachel, duchess of Devonshire to Lord James Cavendish, /late
1722 or early 172.V.

-' Rachel, duchess of Devonshire to Lord James Cavendish. 20
Mar. 1723. Devon. Coll.

-'Rachel, duchess of Devonshire to Lord James Cavendish, 13
Feb. 1724, Devon. Coll.

:s Rachel, duchess of Dev onshire to Lord James Cavendish, /late
1722 or early 1723/.

-''Many details on the positions and actions of the second duke
of Devonshire and, in the next section, of the duke of Kent are
reported in the annual volumes of ////• Historical Register, Chronological
Diary, published in London.

Cavendish

Charles Cavendish brought the same attitudes to
public service, and we see them in his son Hcnrv
as well. Without our knowledge of their way of
viewing themselves in their society, we may easily
misinterpret — as has been done by earlier biogra-
phers — Henry Cavendish's life in science. Although
Henry Cavendish would not have had in mind
specifically his family's political principles, there is
nonetheless a similarity of aspirations; if the Cav-
endishes secured the ancient rights and laws of the
kingdom, why should not a Cavendish aim as high
in any other endeavor, including the search for the
fundamental ruling laws of nature?

William, second duke of Devonshire, brought to
whig politics not only his own political but also his
wife's strong personal interest. Rachel Russell had
been brought up not to forget the injustice done
her family by her father's execution in 1683 at the
hands of the Stuarts. Nine years old at the time of
her father's trial and execution, she had been
taken by her mother to see her father imprisoned
at the Tower. 30 Her mother had later written about
her: "Those whose age can afford them remem-
brance, should, methinks, have some solemn
thoughts for so irreparable a loss to themselves and
family." 31 Attending the proclamation of William
and Man. as king and queen, Rachel pronounced
herself "very much pleased" to see them take the
place of "King James, my father's murderer." 32
Lady Russell tried to turn the family's suffering for
the whig cause to her son-in-law's political
advantage. Soon after William Cavendish's return in
1691, his "friends," including Lady Russell, exerted
their influence to have him stand for member of
parliament for Westminster. Lady Russell warned
off other potential whig candidates, reminding
them of their political debts: "I believe the good his
father did in the I louse of Commons . . . will be of
adv antage to this /William Cavendish's candidacy/.
And it will not hurt his interest that he is married
to my Lord Russell's daughter."" The Russell
name was then thought so great a guarantee of
political success that in 1695 two of the principal
government whigs unsuccessfully tried to talk
Lady Russell into letting her fifteen-year-old son
stand for parliament, certain that he would be
elected and bring in another whig with him. 34

The services of the Cavendishes and the
Russells received official recognition in 1694, when

not only William's father was raised to a dukedom,
but also Rachel's grandfather William Russell
became the first duke of Bedford, an honor that
would have gone to her father if he had lived.
Devonshire already held the office of lord high
steward in the royal household. In 1695, when
William III was about to go to the Continent for
half a year, Devonshire was appointed by him to be
also one of seven lord justices to serve as regents
during the king's absence, in charge of the army and
navy, the economy, and public order. Devonshire
continued in that function during the king's
absences in succeeding years as well, joined in 1697
by Rachel's uncle Edward Russell, the man who
had smuggled the whigs' invitation to the English
throne to William of Orange in 1688, and who was
now a member of the governing whig "Junto." ""

Of the principles the second duke of
Devonshire promoted, none was so important as
the strict limitation of the power of the monarch. In
that century two kings had been deposed for their
absolutist practice, and no sensible politician
wished for a repetition. There had been more than
enough political and religious turmoil for a century
if not for forever; the century ended by entering
upon a new age, one committed to tolerance
instead of fanaticism, in which political power was
invested in reasonable men from the propertied
classes, who were thought to have most at stake in
ensuring order and responsibility in the public
realm. Power, Devonshire and like-minded fellow
politicians believed, was properly located in
parliament, which represented the power of the
landed aristocracy, and they strove to increase the
power of parliament as a defense against any
resurgence of royal absolutism. Since the Glorious
Revolution, parliament was no longer a body that
met occasionally to raise new taxes but a body that
met regularly as part of ongoing gov ernment. It did
not serve the executive but checked it; it served the

"'Mary Berry. Some Account of the Life of Rachael Wriothesley I .tidy
Russell . . . (London. 1H19), 36.

''Lady Rachel Russell to her daughter Rachel Russell, /16K7/, in
Some Account . . . l./id\ Russell, HI .

'-'Rachel, Duchess of Devonshire to a friend. Keb. 16K9. in Some
Account of . . . Liiely Russell, 93-%, on 95.

"Lady Rachel Russell to Mr Owen, 23 Oct. 1691, in Letters of
Lady Russell. 532-34, on 533.

' 4 \Villiam L. Sachse. Lord Somen: A Political Portrait
(Manchester: Manchester I University Press, 1975), 107.

"Geoffrey Holmes. British Politics in the Age of Anne (London:
Macmillan. 1967). 235.

The Dukes

aristocracy, who dominated it. 36 Devonshire could,
however, act to temper the power of parliament in
the name of a higher authority, the laws of the land,
the constitution, when he saw parliament behaving
like earlier monarchs, infringing on the rights of the
greater "commons," the people of England.
Devonshire defended the constitutional distribution
of authority with ringing appeals to rights and
liberties. The assertion of parliamentary power, the
continuing resistance to royal prerogative, and the
call to constitutional responsibility were, in effect,
Devonshire's public career. In making political al-
liances to this end, he was serving the interests of his
family and caste and, he was convinced, the people
of England. He was, in his eyes, a man of principle.

Although William and Mary had come to
the English throne with the support of the vvhigs,
William would not govern with that party only.
William and Mary had accepted the English crown
on conditions dictated by the Declaration of Rights
(made into a statute known as the Bill of Rights) of
a governing convention; these conditions consti-
tuted a reduction of royal power which, to no one's
surprise, annoyed the king and made him sus-
picious of any further encroachments in the
following years. Also to no one's surprise, the king
sought his friends elsewhere than among the
whigs, namely, among politically neutral men or
tories.' 7 However, by 1695, several whig leaders had
maneuvered themselves into positions at court with
power to set policy for the next few years. In
parliament, on the other hand, they faced op-
position not only from the tories but also from the so-
called country whigs, loyal to the interests of Eng-
land above those of their foreign monarch, and they
needed all the votes they could muster to carry their
program. 38 Devonshire could provide them with at
least two that year: both of his elder sons, William
and Henry, were now of age and duly elected.

William Cavendish, now marquess of
Harrington (we cannot avoid a proliferation of
titles: the duke of Devonshire had a subsidiary,
lesser title, marquess, which his eldest son was
allowed to borrow as a courtesy title), began his
parliamentary career in the winter of 1695 as
member for Derbyshire, his home county. He was
elected as a whig when whigs, including his own
father, made up the greater part of the court party,
but this court was soon to learn — as others had
before and would again in the future — that

Cavendishes were no slavish followers of any one
party in parliament or ruling group at court. They
acted out of what has been described as the "deep
consciousness of rank" of the aristocracy of the
time, the Cavendishes with better reason than some-
others. They "possessed a sense of themselves as a
caste apart which gave them an arrogance, a
panache, and an almost unconscious egoism which
allowed them to live and to die with little thought
of any standards or loyalties but their own."" Their
loyalties they identified with the good of the country.

The principle that Harrington applied with
annoying regularity to the issues most important to
the court was, as we have pointed out, that of
vesting as much power as possible in parliament,
and away from the crown. The Declaration of Rights
had left open to dispute the exact relationship
between king and parliament, and Hartington
stood guard over the gaps.

Almost immediately after his arrival in
parliament, an issue of royal prerogative arose over
the establishment of a council of trade. Factions in
parliament were dissatisfied with the lack of
protection for trading vessels during these years of
war and wanted to set up a commission. But the
king, who had procrastinated on the problem until
the Commons lost patience and acted on its own,
rejected the parliamentary establishment of such a
commission as an encroachment upon his pre-
rogative. When the question was put to a vote,
Hartington (and his brother, an earlier Henry
Cavendish) voted that the members of the proposed
commission should be appointed by parliament,
not the crown. 40

Another serious dispute between parliament
and the crown was over the size of the army that
William wanted to retain after the peace of Ryswick
in 1697, as many as 30,000 men, constituting a
standing army. The king's request met with the

V, M. L. Bush. The English Aristocracy: A Comparative Synthesis
(Manchester: Manchester University Press, 1984), 199-200.

"The Divided Society, Parties and Politics in England 1604-1716,
eds. Geoffrey Holmes and VV. A. Speck (New York: St. Martin's Press.
1968), 98. Stephen B. Baxter. William 111 and the Defense of European
Liberty 1650-1702 (New York: Harcourt, Brace & World, 1966), 2.S6.

'"Holmes and Speck, eds. Divided Society, 16-17. Sachsc,
Somers, 113.

3, J. H. Plumb, Sir Robert Walpole. Vol. 1, The Making of a
Statesman (London: Cresset, 1956). Vol. 2, The King's Minister
(London: Cresset, 1960), 9-10.

4ll Hcnry Horwitz, Parliament, Polity and Politics in the Reign of
William III (Newark: University of Delaware Press, 1977). 165.

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Cavendish

strong objection that such an army had been
forbidden by the Hill of Rights because of the
threat it posed to English liberty. Parliament
settled instead on a much smaller force of 8,000
men, and that bill was so vigorously supported by
I lartington and his brother that they drew a
reprimand from the king. Loyal first of all to
Cavendishes, even above the king, Devonshire
took his son's part and threatened to resign his
office at court. 1 le felt the attack, he said, as if it
had been directed against himself, "for he believed
their reasons were sensible, as the king was
forbidden to maintain a large establishment." 41

During Harrington's second term in
parliament, from 1698 to 1700, the composition of
the Commons was such that the whigs found it
difficult and often impossible to control it.
Encouraged by the king's growing rejection of his
whig ministers, the Commons was in a mood to
break the junto by wearing down its members in a
series of politically motivated attacks, especially
over the royal grants of crown lands in Kngland and
Ireland since 1685. In these debates the question
came up, at least implicitly, of the king's right — or
lack of it — to choose his own advisors. The
Commons argued that they needed to guard against
"an ill ministry, and the influence of foreigners."
The reference to foreigners was part of a more
general resolution aimed at removing the lord
chancellor John Somers from office. It would have
been put aside along with the rest of the resolution
when the Commons voted against it, if Hartington,
who voted in favor of Somers w ith the majority, had
not insisted on the question of foreign influence.
He introduced one more resolution, which called
for the exclusion of all foreigners except Prince
Ceorge, the future queen Anne's Danish husband,
from the king's councils in Kngland and Ireland.
After giving a vote of support to a minister whom
the king wanted to be rid of, the Commons now
supported without contest Hartington's resolution
against councillors whom their foreign king might
want. 4 -' The implication was that it was the
Commons, not the king, who would make or break
ministers. But the king had not yet come around to
that view: a few weeks later he dismissed Somers.

By 1701 the whigs had lost control of the
Commons altogether, yielding it to a combination
of tories and the so-called country party. As the first
item of business in importance, this coalition was

confronted once again with the task of settling the
Protestant succession to the English throne, for
Anne's last surviving child had died the previous
summer. Hartington moved to take up the
question in committee. When the committee of
the whole house met a few days later, it resolved
that in addition to "a further Declaration . . . of the
Limitation and Succession of the Crown in the
Protestant Line" it would make "further Provision . . .
for Security of the Rights and Liberties of the
People." The latter was taken up first: in nine
resolutions, the Commons placed further restric-
tions on the crown, including a definition of the
role of the privy council, the exclusion of foreign-
born persons from holding office or from receiving
land grants from the crown, and the requirement
that the king seek the consent of parliament for
waging wars in defense of other than British
territories. 4 " , Britain then had a foreign monarch and
was about to settle its crown on yet another foreign
royal family, that of Hanover. Past experience and
common sense dictated that the protection of the
"Rights and Liberties of the People" be carefully
set down in law.

Hartington's constant concern with questions
of rights extended to the "Rights and Liberties" of
individuals, or, as he put it, "of all the Commons of
Kngland," and not merely of the House of
Commons as a body. In the parliamentary session
of 1701-1702, a particular case raised the question
of the right to initiate a dissolution of parliament.
The suggestion by the tories that that right rested
exclusively with the king caused Hartington to
move a resolution asserting the subjects right to
address the king for "the calling, sitting, and
dissolving" of parliaments. In reaction to the
protracted impeachment proceedings against the
whig ministers Somers and Orford (Hartington
voted for the acquittal of both, the latter his relative
Edward Russell), Hartington moved another
resolution asserting the rights of individuals, this
one even more fundamental than the first, namely.

41 1 lorwitz, Parliament, 250. Sachse, Somers, 130-32.

4 -l lorwitz, Parliament, 265-68. Sachse. Somers, 100-64.
Journal of the House of Commons 13:375 (3 Mar. 1701). Horwitz,
Parliament, 2M-K4. Hartington's wish to exclude foreigners from high
office did not prevent him from welcoming them into the army. When
in 1702 a tory member of the House proposed to deny foreign-born
military men commissions in the British army. Hartington, leading the
whigs, objected vigorously. George Maeaulay Trevelyan, England under
Queen Anne, vol. I: Blenheim (London: Longmans, Green, 1930), 205.

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The Dukes

the subject's right to "a speedy trial" of "any
accusation," including impeachment, against him.
The Commons approved both resolutions without
debate. 44 In 1704 yet another case caused
Hartington to defend an individual's right to vote
as standing above the privileges of the Commons.
"As long as I live, I shall be as tender of the
privileges of this house as any body," he said in the
Commons, but he added, "I must confess, I think
the liberty of a cobler ought to be as much
regarded as of any body else; that is the happiness
of our constitution." In this case of Ashby and
White, an elector who claimed that he had been
denied his right to vote had taken his complaint to
the courts. The Commons insisted that the actions
following from this infringed on the privileges of
the Commons, that the matter should have been
brought before them. Hartington saw the question
as "a matter of great consideration." "For when a
person offers his vote at an election, and is not
admitted to give it, and upon such refusal brings
his action in the courts in Westminster-hall, (which
I take to be the present case), if giving judgment
upon it be contrary to the privileges of this House,
then it is pretty plain, that our privileges do
interfere with the rights of the people that elected
us." The aggrieved party in Harrington's opinion
had no recourse but to the law. His careful
reasoning was wasted on his colleagues, but he
persisted. When the matter was moved from
committee to the whole house, he spoke up again:
"I do not expect the House will be of a different
opinion from the Committee; but I think it is my
duty, when I apprehend what you are doing will be
of ill consequence to the constitution, to give my
dissent in every step. 1 think it will be dangerous to
the very being of this House." The argument was
simple: if the Commons could affirm or deny an
individual's right to vote, then "by the influence of
officers they might have filled this House with
what members they had pleased, and then they
could have voted themselves duly elected." 45 He
was defending — in vain, as far as his colleagues in
the Commons were concerned — what a supporter
of his called the "birthright" of the people of
England. Lord Somers, trained in the law, agreed
with Hartington and gave a scholarly defense of
their position in the House of Lords when the
Lords considered the outcome of the ease in the
Commons. Somers carried the conclusion one step

further than Hartington. Denying an elector his
right to vote, Somers concluded, was equivalent to
denying him his right to his estate, since the law had
"annexed his Right of voting to his Freehold. " 4( '
Somers was speaking as a lawyer, citing precedent;
Hartington, not referring to the connection
between landed property and the right to vote,
may have supported a more liberal view, but, given
the base of Harrington's power, we have no reason
to think he had any serious disagreement with
Somers 's legal position. 47

Acting often independently of party and
almost constantly in opposition to the court was no
route to high office or political power. Hartington
did not want a place as courtier at William's court, as
he demonstrated when he declined a sought-after
"Bedchamber place" offered him in the summer of
17()0. 4X Court posts at that level always went to
peers; if Hartington had accepted the post, he
would probably have been elevated to the peerage,
which would have forced him to move from the
Commons to the Lords. He would have had to
leave a sphere of political action where he was
most needed, where the whigs required additional
strength. (The duke of Kent's eldest son, Anthony,
in 1720 accepted a post as gentleman of the
bedchamber to Ceorge I and was prematurely, i.e.,
in his father's lifetime, elevated to the peerage and
the House of Lords as Lord Harold.) Hartington
may have been holding out for a political post — in
1701 rumor had it he was being considered for
secretary of state— but that the king denied him.

Possible disappointment along with the
influence of new associates may have changed
Harrington's political activities, if not his principles,
after 1700. He became part of a group of politicians
and friends that included Robert Walpole, all

J4 I lorwitz, Parliament, 302-3. The Manuscripts of the House of
Lords, vol. 4 (New Series), 1699-1102 (London: His Majesty's
Stationery Office, 1908), 300.

'"•Cobbeft's Parliamentary History of England. Prom the Sorman
Conquest, in 1066, to the Year 1803, vol. 6: Comprising the Period from the
Accession of Queen A nne in 1 70 J, to the Accession of King Ceorge the h irst in
/7/-/(London, 1810), cols. 256-57. 301.

"'Sachsc, Somen, 225.

47 An important precipitant of the Revolution of 1688 was James
II 's interference with the privileges of the traditional ruling class.
The Cavendishes along with their kind "combined to create, in the
Revolution Settlement, government of the property-owners, for the
property-owners, by the property-ow ners." VV. A. Speck, Tory Whig.
The Struggle in the Constituencies 1701-1715 (New York: St. Martin's
Press, 1970), 3.

w HorwitZ, Parliament. 276.

associated with the well-known political club known
as the kit-Cat (Hub of whigs. 4 '' Walpole enjoyed
the political support of Orford, Hartington's
relative, and in 1702 Walpole had an opportunity to
return the family favor by ensuring Hartington's re-
election to the Commons. A strongly High-Church-
oriented electorate, including the bulk of the
gentry, had just turned Harrington out of his seat as
Member of Parliament for his home county of
Derbyshire, a seat that must have seemed to him
as though it ought to have been his birthright. The
details of the election suggested fraud. Six
different polling places had been designated for
the election, one for each hundred, but in the end,
they were all set up in the oppositions' bastion of
Derby, in booths and on tables in and around the
same hall, and well away from the country places of
the Cavendishes and the Manners, the two leading
aristocratic families of the shire whose respective
eldest sons were the whig candidates for the
county. 50 Harrington petitioned the Commons to
review the Derbyshire election. The opposition
quickly retaliated with a petition of their own,
charging that Hartington's brother Lord James
Cavendish had been illegally elected for the
borough of Derby. 51 Before any further action was
taken on either case, Walpole's fellow Member of
Parliament for Castle Rising declined to sit, and
Walpole secured the seat for Harrington. Returning
to the Commons as the second member from
Walpole's own constituency meant that Hartington
now, albeit only for a few months, owed his seat in
parliament not to family interest and local power,
but to political loyalty, circumstances that his father
Devonshire found "humiliating," 52 but which
speak for the common sense of the son. The
accession of Anne to the throne in 1702 brought
new general elections; this time Hartington
accepted the patronage of the duke of Somerset
and was returned for Yorkshire, 53 a more dis-
tinguished county seat, which he retained until, at
his father's death in 1707, he moved to the House
of Lords as the second duke of Devonshire.

During the five years remaining to him in
the Commons, Hartington became firmly associated
with Walpole and the whigs. In those years the
whig junto regained its influence and even some of
its power. A minority in the Commons, the whigs
controlled the Lords and shared the ministries with
moderate tories willing to compromise. That the

Cavendish

five junto lords were all in the upper house left
room in the Commons for their juniors to lead whig
issues through the debates. The opening was filled
especially by Walpole and Hartington, who were
becoming leaders among the younger whigs in the
Commons. 54 Hartington and Walpole acted with a
few men of like mind as well as close family and
political ties such as Hartington's brother-in-law
John Manners, marquess of Cranby, Walpole's
brother-in-law Sir Charles Turner, their fellow
Norfolk whig Sir John Holland (holding "sentiments
& principles [that] are the same together with my
Ld Hartington, yrself [Walpole] . . ." and voting
"according to yr wishes"). 55

Harrington's activities in the Commons in
these years give us a good idea of the political role
he chose for himself. He rarely participated in the
committee work on so-called private bills, which
dealt with local problems such as bridge repairs or
with questions of individual estates. He preferred
to take up general questions, such as the Protestant
succession and the rights of non-conformists. 56
Hartington and his associates in the Commons
battled unsuccessfully against the bill to prevent
"occasional conformity." Hartington and Walpole
acted as liaison to the whigs in the Lords, who on
this issue were led by the duke of Devonshire and
who killed off the bill every time the Commons
sent it up. The bill, one of the measures of greatest
priority for the queen and the tories, was aimed at
the practice of non-conformists occasionally to take

4 '1 lolmes, British Politics . . . Anne. 297.

x>The Victoria History of the Counties of England, Derbyshire, ed. W.
Page, vol. 2 (London: Constable, 190.5). 142.

51 3 Jan. 1 702, House of Commons Journal 13:649.

"Dennis Kuhini, Court and Country I6HH-I102 (London: Rupert
Hart-Davis. 1967), 245.

^Coffins's Peerage of England: Ceneologieal, Biographical, and
Historical, 9 vols, ed. K. Brydges (London, 1X12) I: 354. Holmes and
Speck, eds.. Divided Society, 47. Bickley, Cavendish. 186.

"Plumb, Walpole 1:112.

55 1 lolmes, British Politics . . . Anne. 233.

^'The committees he was on in 1792, after Anne had succeeded
to the crown, for example, were the committee to reformulate the
oath of loyalty to the queen and the Protestant succession, and three
committees to draw up addresses to the queen, the first an address of
condolence to the queen on the death of William III, the second, in
March 1702, a reply to her address to the Commons, and, most
important, the third, in May 1702. an address to assure her that the
Commons "will, to the utmost, assist and support her" following her
declaration of war on France. (One of the committees on which he
served in 1702 — "for the better Discovery of all Lands, and other
Revenues, given to Foppish superstitious Uses, and for applying the
same for the Support of the Royal Hospital of Greenwich" — brought
Hartington together with Isaac Newton.) 8 Mar. 1702, and following,
HCJ 13:782, 808-1 1, 830, 870.

The Dukes

communion in an Anglican church to avoid the
legal disabilities placed upon them. 57 To the whigs,
non-conformists were important supporters, a good
practical reason, aside from questions of political
principle or religious conscience, to fight a bill that
aimed at depriving them of the franchise. 58 In 1706
Harrington was appointed to the English com-
mission, headed by Somers and other members of
the junto, working for a union with Scotland. With
a Scottish commission, they worked out the Act of
Union, filling the last gap in the agreements that
ensured the Hanoverian succession. Always much
more a party man than his Court-oriented father,
Hartington in his last years in the Commons went
out of his way to assume political responsibility and
a clearly defined political identity. 5 '' Nobody, not
even the junto or the queen, would in the future
find it easy to ignore him.

The year 1707 was to add the aura of power
to Harrington's political activities. Already during
his father's lifetime, Hartington was on occasion
called upon to take his place at the great cere-
monial events of the court. In August of 1705, for
example, the queen proclaimed a "general thanks-
giving throughout this kingdom" for a military
victory. In the procession from St. James's palace to
St. Paul's cathedral, as the eldest son of a duke,
Hartington ranked right below the dukes, and
ahead of the earls (among them the then still earl
of Kent), the queen's ministers, and the bishops.
"The streets were lined by the citty train'd bands,
and at Temple Barr by our lord mayor, aldermen,
and sherifs, who conducted her to church. . .
Among his fellow Members of Parliament,
Hartington moved almost as if he were royalty
himself; Robert Molesworth, a whig M.P but not
an adherent of the junto, wrote to his wife in 1704:

Yesterday being Sunday, the Marquis of
Hartington sent me word about 8 that he intended
to dine with me. I entertained him and his
company as well as I could at so short warning and
sent for several gentlemen of the neighbourhood
to wait on him, who came and dined with him, and
after dinner (about 5 or 6) we all of us conducted
His Lordship a mile or two of his way towards the
Earl of Kingston's, whither he was a-going.' 1 '
He was prepared to take over from a father who
was powerful enough even to stand up to royalty.
"Here lies William duke of Devonshire, a faithful
subject of good princes, and an enemy to tyrants,"
the first duke had ordered inscribed on his tomb. Two

weeks after his death in August of 1707, his body
was sent off in princely fashion, "carried in great
state thro' this citty . . . followed by about 80 coaches,
the lord James Cavendish, his youngest son, was
cheif mourner; the officers of the queen's household
attended with the heralds at arms, who carried the
ensigns of honour belonging to the family," on the
long, final journey from London to Derby that many
Cavendishes took. Two days later, Hartington, now
duke of Devonshire, was called to the queen "to
receive the white staffe as steward of the household,
vacant by the death of his father"; a week later he
was sworn of the privy council; and in October he
took his father's seat in the House of Lords. 62

The court position that the second duke
more or less inherited from his father 6 -' was still a
politically important position during Anne's reign,
because it placed its holder among her constant
political advisors in the cabinet. Altogether,
Devonshire held high office at Anne's and the
subsequent Hanoverian court for more than ten of
the next twenty-two years; that is, from the time
from his succession to the title until his death.

Whereas while he was at court, half of the
time he found himself out of office, in parliament
Devonshire always remained one of the leaders of his
party, judged "a very honest man" and "a very usefull
man." 64 The House of Lords, rather than the court,
was the politically more rewarding scene for the
whigs — and for Devonshire — where their aim was
the same as at court, to retain or to return to power.

"Narcissus Luttrell, A Brief Historical Relation of Stale Affairs from
September 1678 to 1114, 6 vols. (Oxford, 1857) 5:258-59. 264. 273,
362-64, 369, 490-98. Sachse, Somers, ZKV-IZ. Plumb, Walpole 1:112.

58 Henry L. Snyder, "The Defeat of the Occasional Conformity
Bill and the Tack: A Study in the Techniques of Parliamentary
Management in the Reign of Queen Anne," in Peers, Polities ami
Power: The House of Lords, 1603-191 1, eds. C. Jones and D. L. Jones
(London and Ronceverte: 1 lambledon Press. 1986), 111-31, on 111.

W I lolmes, British Polities . . . Anne, ZiZ.

'■"Luttrell, Brief Historical Relation .5:585.

6l Grcat Britain, Historical Manuscripts Commission. Report on
Manuscripts in Various Collections, vol. 8: The Manuscripts of the Hon.
Frederick l.indley Wood; M. L. S. Clements, Esq.; S. Philip Untrin, Esq.
(London: His Majesty's Stationers- Office. 1913), 232.

"Luttrell, Brief Historical Relation 6: 204, 207, 209. 211. 226.
House of Lords Manuscripts, vol. 7 (New Series): The Manuscripts of
the House of Lords, 1706-1708 (London: His Majesty's Stationary
Office, 1921). 97.

61 "My Lord Steward /i.e., the first duke/ dyed yesterday. The
Queen seems resolved that his son shall succeed to his employment,"
the earl of (jodolphin wrote to the duke of Marlborough on 19 Aug.
1707, in Marlborough-Godolphin Correspondence 2:887.

M Thc duke of Marlborough to the duchess of Marlborough. /28
Aug.//8 Sep. 1 707, Marlborough Codolphin Correspondence 2:895.

Cavendish

The accession of George I in 1714 must have
seemed to the whigs like the morning of a long day
of reaping the rewards for their labor on behalf of
the Hanoverian succession. Probably as a matter of
course, Devonshire was on the list of eighteen
regents sitting in for the king until his arrival in
England. (Also on the list were Kent and Orford.)
Soon after, he received back his old positions of
lord steward and lord lieutenant of Derbyshire and
was sworn to the privy council (as was Kent). With
him, most of his junto colleagues as well as VValpole
and his friends returned to high office. 65

Success, however, allowed rifts among the
whigs themselves to emerge. Although eager to
reach a final peace with France, George, England's
latest foreign king, had continental w ars of his own
to fight. Not all of his whig ministers were still
willing to support royal demands toward that end
before the war-weary English people. For a while,
despite disagreements, events further strengthened
the whig hold on the government. The Jacobite
uprising of 1715/16, for example, resulted in the
dismissal of the remaining tories in the ministry,
and in the summer of 1716 Devonshire resigned
his court office of lord steward to the duke of Kent
to assume the political office of lord president of
the council, the one top-ranking office that since
1714 had still been held by a tory. 66 His new duties
required him to make decisions on all issues before
the government.

During the next ten years, Devonshire,
sometimes in office and sometimes out, was
concerned w ith a broad range of proposals, such as
reduction of the army, reduction of taxes (for the
landed men), trade with Spain (for city men),
building of Whitehall and hospitals (for the poor,
who were to be put to work), pardon for the
Pretender's followers, supremacy of state over
church, and so on. In 1725, when VValpole had a
sensitive task for someone with the access to
government policy and who also had good sense,
he turned to his trusted old whig ally Devonshire.
When the prince and princess of Wales had been
thrown out of the royal residence after the prince's
quarrel with the king, Devonshire was one of the
first to offer the prince and princess his own house
as residence. Eventually they settled at Leicester
I louse where Devonshire became a frequent guest.
Walpole had the tricky job of being the king's
minister and at the same time keeping the goodwill

of the heir to the throne who had been alienated
by the king and removed from official business. He
managed it by secretly keeping the prince in-
formed of state affairs through their mutual friend
Devonshire. Thus, when George I died suddenly
in 1727, Walpole maintained himself in power
under the new king. Devonshire had once more
contributed to stability and an orderly transition of
power. Appropriately the first session of the inner
ministerial circle held to draw up the new king's
speech to parliament met at Devonshire House. 67

Career of the Duke of Kent

Whereas Devonshire sought and acquired
political power and served the whig cause (in his
view) with a fierce loyalty, Kent stood for neither
power, party, nor principle. His political career had
only this in common with Devonshire's: great
ambition, which in Kent's case took the form of
self-interested maneuvering at court. His legacy to
Lord Charles and Henry Cavendish was great
pride in the standing of his family and a breadth of
cultural interests outside politics.

On his return from the Continent in 1691,
Henry de Grey lived the life of a well-to-do private
gentleman for the next ten years, taking up neither
of the usual two occupations of young aristocrats,
the military or parliament. 68 His public life began
almost simultaneously with the reign of Queen
Anne. At her coronation, Henry's father carried one
of the swords of state; four months later, in August
of 1702, his father died suddenly in the middle of a
game of bowls, leaving Henry, his heir, on his way
to the House of Lords as earl of Kent.

Kent took his seat in the Lords with the
opening of parliament in October. From the begin-
ning he took a safe, middle-of-the-road position in
politics, which, given what is known about his
character, seems to have reflected his personal
attitude as much as any design to acquire office.
On the important issue of the occasional

M Plumb, Walpole 1:197, 201-4. Collins's Peerage, 355.

"■Henry Horwitz, Revolution Politicks The Career of Daniel Finch
Second Earl of Sotting/lam, 1647-1730 (Cambridge: Cambridge
I niversity Press, 1968), 250, 252.

'"Plumb, Walpole Z:\bS. Pearson, The Serpent and the Stag, %b.

'•"Thomas Wentworth, The Wentworth Papers, 1 705- 1 '7.19. Selected
from the Private and Family Correspondence of Thomas Wentworth, Lord
Rah. Created in 1711 Earl of Strafford, of Stainboroug/t, Co. York, cel.
James J. Cartwright (London, 1883), 134.

The Dukes

conformity bill taken up during that session of
parliament and the next, for example, he voted for
the bill in accordance with the queen's wishes. 69 For
that reason, he is said to have been a tory in the early
part of his career, but his early voting is of a piece
with his later voting even though he then voted with
the whigs: he was almost always, certainly while he
held office, the queen's man. From a conversation
with a friend during Sacheverell's trial in 1710 it is
clear that Kent, still undecided on how he should
vote on the doctor's guilt, was more concerned to
guess correctly the queen's opinion in the matter
than to formulate his own. 70 In politics, Anne
wished for moderation, and Kent by temperament
agreed with her wishes.

In the spring of 1704, party pressures of the
sort the queen so greatly disliked caused her to
dismiss three high-ranking tory officeholders,
among them her lord chamberlain. Kent was at
Newmarket at the races in April, suffering a fall
from his horse that at first seemed to threaten his
life. 71 Three weeks later he had not only recovered,
but he had been appointed the queen's new lord
chamberlain and a member of the privy council. 72
This sudden and very high leap into a career at
court has been ascribed to the efforts of the
duchess of Marlborough, then Anne's groom of the
stole and friend, and Kent's neighbor in
Bedfordshire. 73 The duchess was never Kent's
friend, although she may have promoted him
because she hoped to dominate him. Other factors
would have recommended Kent to the queen as
well. Anne, who had only just rid herself of one
political group trying to dictate their views to her,
was not about to turn for replacements to strong
party whigs of whose party fervor she was equally
suspicious. Kent was a relatively new face at court,
without disturbing political associations, and
already of proven loyalty. In his political views,
Kent's also fit those of the queen's lord treasurer,
Godolphin, who was involved in appointments.
Robert I Iarley, appointed secretary of state in the
same shakeup, wrote to him at the time: "I am glad
that My Lord Treasurer will choose moderate men
to carry on his Ministrye, which is approved by all
people hithertoe, but those who are very much
inclined to passion, and Selfe Interest." 74 They
agreed that service to the queen should come
before party loyalty, undoubtedly the reason why
Kent allowed himself "always" to be "governed by

Lord Treasurer and that party whilst he was
Chamberlain." 75

Kent's office of lord chamberlain was that of
"greatest honour and dignity" at court, awarded as
a sign of royal favor and always to a person of very
high rank (after Kent's tenure it was always held by
a duke). 7 ' 1 He received emoluments of over £1,000
in the form of money or plate, a pension, lodgings,
and, because of his daily access to the queen, the
opportunity to gain whatever he could through the
sale of offices. The office of lord chamberlain
controlled by far the largest department of the four
highest administrative, as opposed to political,
offices at court (the others being the lord steward's
department consisting of the household "below
stairs," the stables under the master of the horse,
and the royal private apartments or bedchamber
under the groom of the stole). As lord chamberlain,
Kent found himself in charge of all appointees and
employees as well as of all daily and ceremonial
affairs associated with the public rooms of the royal
residence "above stairs"; his department also
included personnel and functions not directly a part
of the royal household, such as the physicians,
surgeons, and apothecaries to the court, the court's
mathematical instrument-maker or the court poet
(in all, at the time of George I, over 600 persons, and
not many fewer before) and the general supervision
over theaters. The annual budget of the lord
chamberlain's department was well over £50,000.

An earl or duke was not expected personally
to carry out the many duties of the office; "dukes
did not open doors for themselves." 77 Most of the
work was left to the vice chamberlain and members
of the staff. But the lord chamberlain did supervise
the overall coordination of the work and had to be

"I lolmes, British Politics \nne, 102.

n The Wentworth Papers, 146. Kent voted for conviction, as the
queen wished, but against her opinion on the severity of the penalty,
which he may have come to regret. Geoffrey Holmes, The Trial of
Doctor Sacheverell (London: Kyrc Methuen, 197.M. 1 16. 210, 285.

71 1 .uttrell. Brief Historical Relation S:4 1 0.

"Ibid. 417-18.

"Holmes, British Politics . . . Anne. 211.

7J ,Sheila Biddle, Bolingbroke and Hurley (New York: Knopf,
1974), 103.

" The Wentworth Tapers, 134.

;,, John M. Beattie, The English Court in the Reign of George I (Cam-
bridge: Cambridge University Press, 1967), 24. Much of our information
about the office of lord chamberlain below is derived from Bcattic's
chapter on this office: " The Departments of the Household. I. The
Chamber and the Bedchamber." 23-65, and elsewhere in this book.

"Ibid. 40.

Cavendish

in attendance practically year round. On the Sunday
after his appointment, Kent for the first time
"handed her majestie to chappel." 78 He arranged
any public ceremony the queen desired, and he
acted as her escort. In her exchanges with the
I louse of Lords, it was Kent as her lord chamberlain
who acted as go-between, a responsibility attended
by a great deal of ceremony. W hen, early in his
tenure, Kent on one occasion sent a message to the
Lords by another peer, informing them of the time
the queen had fixed for them to attend her, his
messenger — and by implication Kent himself —
was immediately reprimanded by one of the dukes,
"a man jealous of the Orders of the House," for so
"irregular" a procedure.' 1 ' Greatly devoted to his
gardens at his country estate of Wrest in
Bedfordshire but kept in the city by his office, he
could do no better late in May than to have his
wife's account of the work he was having done
there and learn that "the country is very pleasant
and sweet for the Honeysuckles are in perfection."
"I desire you in return to lett me heare from you &
tell me what politicks goes forward," she added,
sympathetic to his plight. 80 Another part of his
duties was that he frequently had to entertain at his
own expense. I le inaugurated his tenure as lord
chamberlain in style: a month after his appointment
he "treated her majestie and the court upon the
river Thames, where were near 1000 barges and
boats, with all sorts of musick and eatables" on
what one hopes was a lovely day late in May. 81

The office of lord chamberlain had at one
time included what was by the early eighteenth
century a separate department of the royal bed-
chamber under the groom of the stole. There were
still areas where the lines of authority of the two
departments were not clearly sorted out, and there-
was a certain amount of rivalry between the holders
of the top offices. The difficult duchess of
Marlborough, holding office alongside Kent, made
his tenure especially hard and tarnished his
reputation. She apparently thought that he would
be easy to control. Godolphin's remark to her about
Kent's appointment that the "whole town was
thoroughly disappointed about Bugg" would not
have been made if (iodolphin had known her to be
holding Kent in high esteem. 82 Godolphin himself
and the duke of Marlborough, Anne's chief ministers
then, certainly did not, for they never invited Kent
into the cabinet, which was highly unusual

behavior toward one of such high office. 83 Within a
few years, the duchess's influence with the queen
began to wane, while Kent proved to be less
malleable than the duchess may have expected,
creating tension and eventually downright hostility —
at least on the Marlboroughs' side — between them.
When Kent, for example, ignored the duchess's
recommendation in making an appointment, she
sent him a message "of a very rude nature. " fS4 Kept
informed of the duchess's complaints while with
the army on the Continent, Marlborough was
angered for months by Kent's wish for the Garter
in 1707: "I think it should not be given til the
Queen is sensible of the sham it would be to let so
worthless a creature ... /as Kent/ so much as expect
itt," he wrote to his wife, no doubt hoping that his
wife would make the queen "sensible" of the
worthlessness she herself apparently did not
perceive.* 5 Kent quickly learned to guard his
interests and not to trust the duchess. Settling a
theater dispute in 1 706, Kent "was big of the plot,"
reported the theater's manager who worked with
him, "and was afraid if any body shou'd let it be
known at Court before him, he shou'd be Robbed
of the glory of Establishing the Stage upon a foot of
going on." When the plot succeeded, "he told it at
the Dutchesse of Marlbro's" (who tried to
influence the theater as well although she had no
jurisdiction over it), no doubt with a note of
triumph. 86 The duchess absented herself from the
court after 1708 because of a bitter quarrel with the
queen. Kent, linked to the more reasonable

7 "Luttrell, Brief Historical Relation 5:417.

'''William Nicholson, The London Diaries of William Nicholson
Hishop of Carlisle 1702-1718, ed. C. Jones and G. Holmes (Oxford:
Clarendon Press, 1985), 257-58.

""Jemima, duchess of Kent to Henry, duke of Kent, 18 Mav
/probably 1708/, Bedford Record Office, Wrest I'ark Collection. L
30/8/35/3.

"Luttrell, Brief Historical Relation 5:42°-.

82 The . \larlborough-Godolphin Correspondence 1 :284.

"Holmes, British Politics . . . Anne, 111.

Hi l'apers of Sir William Trumbull, part 2. p. 866.

8S The duke of Marlborough to the duchess of Marlborough. 14
May 1708, in The Marlborough-Godolphin Correspondence 2:895, 972.
Toward (iodolphin. Marlborough was more restrained, suggesting
that he was either humoring his wife or aware that Godolphin
thought somewhat better of Kent than he. On the same day on
which he wrote to his wife that "it would be scandelous to give it
/the Garter/ him /Kent/, since he has no one qualliry that deserves
itt," he wrote to (iodolphin, not mentioning Kent's name, "I w ish for
the service of the Queen, that she may have no thoughts of disposing
of the blew ribons, til she may find the giving of them be a
satisfaction to herself, or of some use to her business." Letters of 8
•Sep. 1707, ibid., 894-95.

The Dukes

J 7

Godolphin, was safe for another two years, and
then the queen waited until Godolphin was out of
town before she asked Kent to resign.* 7

That Kent's hold on his office after 1707
was at times only tenuous had much to do with the
constant political shifts between tories and whigs
in their struggle for power during Anne's reign.
Any high court office was a potential foothold for
political domination. Kent was not a political man,
and to those of either party who were, his office
must have seemed to be a wasted opportunity. In
1708, when the whigs were trying to force their
way back into government, Kent feared for his
office: "My Ld Chamb: is in a Tottering way, I
know he expects to be out which he has not a mind
to," someone who knew him wrote in July. 88 In
December gossip had it that "So many think
themselves fit for Chamberlain that the fear of dis-
obliging a multitude still keeps in Lord Kennt." 89
It may also have been the queen's stubbornness
with which she was opposing the rest of the whigs'
demands for office then that kept Kent in. Only in
1710, when party politics had brought the tories
into the ascendancy again, the queen yielded to
Harley and gave Kent's office to a tory duke,
dismissing Kent, as he said, "with all the marks of
kindness.'"* Kent, Godolphin reported to
Marlborough, "is extreamly nettled, and is not shie
of expressing a good deal of resentment" against
Harley and Somerset, "who he thinks have been
the chief occasion of it." 91 Sparing the queen was
wise: for sacrificing him, she made him duke of Kent.

In the last four years of her reign, Kent at
times acted the party man, voting with the whigs in
the House of Lords. But the queen could still sway
him, too: "I am told that the night before the
Parliament meet the Queen sent for the D. of Kent
and talked to him a good while, and the next day
he voted with the Tories," a lady at court reported
in 171 1. 92 Along with receiving further honors from
the queen after his dismissal, Kent was one of only
a few whigs who still held positions of honor (if not
of profit) after the queen had turned her govern-
ment over to an unabashedly tory administration. 93

Kent's appointment to lord chamberlain
coincided with the beginning of an important
cultural development in which he was to play an
official part; namely, the introduction of Italian
opera at English theaters. The lord chamberlain's
supervision of theaters was only a small part of his

official domain and need hardly have involved him
personally at all. As it was, he left much of the day-
to-day business of singers' and actors' complaints
over contract terms or disagreements with the
theater managers to his vice chamberlain Thomas
Coke. 94 But Kent had long taken an interest in
music in his private life, which he could indulge in
his official capacity as well.

Kent and his wife Jemima Crewe from the
beginning of their marriage had a common love of
music. Every month, sometimes several times a
month, they attended "musick meetings," the
then fashionable subscription concert series
arranged by music lovers such as Thomas Britton
who could present Handel. At times they spent
more money on "a Musick book and Italian
songs" than on all books on other subjects com-
bined. 95 Away from London, the "Nightingale"
had to "supply y e want of Margarita" (Francoise
Marguerite de I'Epine, one of the leading singers
of the day) for Jemima. 96

The principal theaters over which Kent's
new office gave him control in 1704 were those at
Drury Lane and Lincoln's Inn Fields, to which the
Haymarket was added in 1705. Lincoln's Inn
Fields was closed for most of Kent's tenure. Drury
Lane was then performing both plays and English
operas, which were not operas in the modern
sense, but spoken plays with musical numbers and
masques. When the Haymarket opened it followed
suit. All-sung or "Italian" operas had until then
been produced only abroad, but in the season of
1704/5, the owner-manager of Drury Lane,
Christopher Rich, successfully staged the first

"■Judith Millions and Robert D. Hume, eds.. Vice Chamberlain
Coke's Theatrical Papers 1706-1715 (Carbondalc and Edwardsvillc:
Southern Illinois University Press, 1982), 12.

"The earl of Godolphin to the duke of Marlborough, 17 Apr..
1710, in The Marll/orough-Godoiphin Correspondence 3:1463.

""Milhous and Hume, Coke's Theatrical Papers, 1 13.

"'' Thomas Butler to Sir William Trumbull, 28 Dec. 1708, in
Papers of Sir William Trumbull, 867.

'"'Letter by Peter Wentworth to a friend, end of Sep. 1710. in
The Wentworth Papers, 146.

"The earl of Godolphin to the duke of Marlborough, 17 Apr.
1710, in The Marl/iorough-Codolphin Correspondence, 1464.

'''The Wentworth Papers, 222.

'"Holmes, British Politics . . . Anne, 436-39.

M Milhous and Hume, Coke's Theatrical Papers, xxi-xxii, xxvii, 106.

■"Accounts from 1692 to 1697, p. 84 and passim. Bedfordshire
Record Office, Wrest Park Collection, L 31/129.

^Jemima Kent to the marquis of Kent, Wrest, 18 May /probably
1708/, Bedfordshire Record Office, Wrest Park Collection, L
30/8/3S/3.

Cavendish

Italian opera in London. The Haymarket
immediately put on Italian operas of its own. 97

From the start, Italian operas appealed
primarily to fashionable society: "the Great chiefly
incourage them," a contemporary periodical
reported, perhaps because "the Kxpence of that
Diversion is a little too great for such as declare for
exact Oeconomy." 98 Nevertheless, theater managers,
along with their official patron, Kent, and other
aristocratic supporters expected Italian operas to
become popular and a great financial success,
especially if they could induce the best Italian
singers to accept engagements at the London
theaters. For a short time, their expectations were
met, but at a price. Rich, at Drury Lane, by putting
on both operas and plays, profited despite staging
expensive operas because he did not pay the actors
whom he had under contract for plays. The
Haymarkct's v enture into Italian opera was a
financial failure. Both actors and singers com-
plained to the lord chamberlain, without whose
permission they could not leave their engagements
to earn money elsewhere. Kent's solution to their
problems was a ruling, which became known as the
Order of Union; by it, one theater, Drury Lane,
would perform only plays, and the other,
Haymarket, only operas, and they would avoid
competing with one another by not both playing
the same night. Kent's ruling earned him warm
gratitude from the actors, even the dedication of a
play by the actor-playwright Colley Cibber. 99 But it
was to create problems for opera, even though it
was meant to strengthen it: opera was set on a
financial course it has had to follow ever since,
sustaining itself through philanthropic or state
support. The foreign singers brought in as the star
attractions, intended to keep opera profitable,
asked for very high salaries, several times those of
actors, the Fnglish "Climate being much wors than
any other for voices" 100 and, no doubt, Fnglish
aristocrats wanting the novelty of their singing.
When they could not get the salaries they asked
for, they sang at "musick meetings," threatening
the existence of the opera, which could not get
singers at "reasonable sallarys" if they could earn
more elsewhere. To protect the opera, Kent tried
several means. He stopped competing concerts;
with the owner-manager of the Haymarket, Sir
John Vanbrugh, he organized an opera company
including a full, regular orchestra; and he thought

of creating year-round opportunities for singers to
earn money, during the summer as well as during
the regular opera season. "Voices are the things at
present to be got," Vanbrugh wrote to the Fnglish
envoy at Venice, who was to negotiate with the
Italian singers; "if these Top ones come over, 'twill
facilitate bringing the Queen into a Scheme, now
preparing by my Ld Chamb: and Others, to have
Concerts of Musick in the Summer at Windsor,
twice a Week in the /queen's/ Appartment. There
is no doubt, but by some such way as this, if the
best Singers come, they will tast of the Queens
bounty." Within two or three seasons it had
become clear that opera could not support itself,
and Vanbrugh appealed to Kent to "move the
Queen ... to give a Thousand Pounds a year
towards the opera support." 101 With an enterprise
so new it took longer than Kent's term in office to
put it on a regular footing, but he kept it alive,
even when managers like Vanbrugh were driven off
by their financial losses." "'-

After being out of court office during the last four
years of Queen Anne's reign, Kent's reputation as a
"staunch court man" earned him a place on George
I's list of eighteen regents who were to govern in
his place until the king's arrival in England.""
Under an administration of clear political orienta-
tion such as the whigs's immediately after the
accession of George I, a politically lukewarm, if not
disinterested, courtier such as Kent had to be

'■Our discussion of opera at London theaters at this time is
based primarily on Millions and Hume. Coke's Theatrical Papers.
"Ibid, 81.

'"Colin (libber: Three Sentimental Comedies, ed. M. Sullivan (New
Haven: Vale University Press, 1973). 177-79. The play was Cibber's
The Lady's Last Slake or, the Wife's Resentment. The dedication, which
describes the actors' difficulties that Kent was trying to end by
decree, also describes Kent as the mild-mannered man he was: "My
Lord," Cibber w rote, "there is nothing Difficult to a Body of English
People, when they are unanimous, and well commanded: And tho'
your Lordship's Tenderness of oppressing is so very just, that you
have rather stay's to convince a Man of your good Intentions to him,
than to do him ev'n a Service against his Will: Vet since your Lordship
has so happily begun the Establishment of the separate Diversions,
we live in Hope, that the same Justice and Resolution will still
persuade you to go as successfully through with it." On p. 1 7H.

""'Millions and Hume, Coke's Theatrical Papers, 4.S.

""Ibid, 74. 1(10. 107.

" IJ Kent was no doubt helped in preserving Italian opera in
London by his shutting down of Rich's exploitative operation at
Drury Lane in 1709. He reunited the actors with the singers at the
Haymarket. which for a time — apparently profitably — put on plavs
alongside Italian operas as Drury Lane had in 1704/.S.

""Ragnhild Hatton, George/, Elector and King (Cambridge, Mass:
Harvard University Press, 1978), 120-21.

The Dukes

satisfied with less than first-rank offices. In the fall
of 1714 the king appointed him to a bewildering
assortment of positions: member of the privy council;
gentleman of the bedchamber; constable, governor,
and captain of Windsor Castle as well as "Keeper of
the Parks, Forests, and Warrens there, and
Lieutenant of the said Castle and Forest"; and lord
lieutenant and Custos Rotulorum of Bedfordshire
(positions which could have been set to music by
Gilbert and Sullivan)." 14 It meant that Kent was
back at court, with regular access both to the king
during his weeks of "waiting" and to court society
for emoluments nearly as large as those he had
enjoyed as lord chamberlain. 105 Two years later,
when the duke of Devonshire moved from the
office of lord steward to that of lord president, Kent
succeeded him as lord steward, reaching once again
the top of the royal household. In 1719 the king
found it politically expedient to reward another
peer with that office, and Kent moved on to lord
privy seal. As in 1710, in 1720 a political shakeup,
this time in favor of the whigs, brought to an end
Kent's career as a courtier.

His many years of service, however, and his
rank created an unofficial but well-understood
obligation toward him at court that continued after
he left office. The royal favors that he claimed
were now for his children. His eldest son Anthony
de Grey, Earl of Harrold, elevated to the House of
Lords as Baron Lucas of Crudwell as early as 1718,
was appointed a gentleman of the bedchamber in
the year in which his father lost his own office at
court. 10 '' Kent was being rewarded just as Queen
Anne had wanted to reward him in 1710, when she
promised him any favor he might wish to ask in
return for his resignation, and Kent could think of
none but a place for his wife as one of the queen's
ladies. 107 A week after his son's appointment, his
son-in-law John Campbell, Lord Glenorchy, profited
as well by becoming envoy to the Danish court. 10 *
That such an obligation was perceived not only by
Kent but was generally accepted as a fact of
political life is illustrated by a court conflict over a
post in 1723. Kent's eldest son died that summer in
an accident, leaving vacant his post as gentleman of
the bedchamber. This left Kent with a "particularly-
strong claim" to the post because, one assumes, it
had been given to his son in acknowledgment of
his own service or possibly even in return for his
relinquishing of his office. 10 *' Kent wanted the post

for his son-in-law John Campbell, Lord Glenorchy.
Glenorchy was a Scot, who as a young man had
been expected to follow his kinsmen in their
Jacobite politics. At the time of his marriage to
Lady Amabell de Grey in 1718, he was considered
a "youth of good sense" and "as to the young lady,"
a tory relative wrote, "I think it more probable he
may turn her than she him, and, if he be a hawk of
the right nest, as I think he is, he will turn her to
purpose and wants not an argument that may be a
good means to make her a very early convert, and
as to his father-in-law, I have no great fear of him,
for I hope Lord Glenorchy has too much sense to be
brought over by him." 110 Glenorchy was a man of
good sense who realized that his future was better
served by the ruling king of England and a father-
in-law in high office than by the pretender in exile
on the Continent. By 1723 Glenorchy was ready to
return to England from his Danish post, and in
August, the king's secretary for the south, John
Carteret, who had been Kent's fellow gentleman of
the bedchamber in 1714-16 and who was now
acting for Kent because he was then with the king
in Hanover, applied to the king to secure the
position for Glenorchy. The king delayed the
decision. In October Amabell wrote to her father:
"My Lord has no longer any hopes of going to
Hanover, which is the greater mortification to him,
because he has y 1 ' less reason to expect to succeed, in
what your Grace is so good as to sollicit for him." 111
But Walpole acknowledged Kent's claim when he
proposed that the duke ought to be compensated
for the post with a pension of £3,000 a year if the
post did not go to Glenorchy. 11 - By 1725, Kent was

m The Historical Register, vol. 2. Chronological Diary, l >, IK. 21
October 1714. pp. 15-16.

""His salary as gentleman of the bedchamber alone was £1.000
a year. Beanie, 'ihe English Court . . . George /, 2 1 1 .

""•The Historical Register, vol. 5, Chronological Diary, 6 June 1720,
p. 24.

1117 The Wentworth Papers, 146-47.

""The Historical Register, vol. 5, Chronological Diary, 1 1 June 1720.
p. 25.

""Beattie, The English Court . . . George /, 151-52.

1 "'Colin Campbell to the duke of Marlborough, 22 Apr., 171X.
Great Britain. Historical Manuscripts Commission, Calendar of the
Stuart Papers Belonging to His Majesty the King Presen ce/ at Windsor
Castle, vol. 6 (London: His Majesty's Stationery Office. 1916),
348-50, on 349-50.

'"Lady Amabell Glenorchy to the duke of Kent, 2 October
N.S. /17Z3I, Bedfordshire Record Office. Wrest Park Collection. L

30/8/8/27.

ll2 Beattie, The English Court ... George/, 151-52.

Cavendish

receiving an annual pension of £2,000, suggesting
that others had recognized his claim as well. 113

Out of political office, except for his lord
lieutenancy of Bedfordshire and the few occasions
when he was called upon to act as lord justice while
the king was out of the country, Kent nevertheless
remained close to court life, and he continued to
attend the House of Lords. 114 Walpole, who never
overlooked anyone who might produce votes for
his party, sought his support as late as 1733. Kent
was still proud even if bitter: "I . . . am very much
obliged to you for thinking I have any interest in
this county worth being desired .... I have no fear
that the country will goe at any time against my
inclination, having never lost any ellection here
these 30 years but I have been thought of late a
person of so little consequence that I think the less
I have to doe in any of these matters the better,
and only desire to live well with all my
neighbours." 11 ^ In his and the second duke of
Devonshire's lifetime a change had taken place in
the criteria of a person of political "consequence":
the high court office and a relationship of trust with
the monarch had at one time signified great
importance; but with the shift of power from the
king to parliament and political parties, the

courtier's real importance was slight unless he
represented party more than the monarch. The
first time Kent had lost high court office, he lost it
to the interest of a royal favorite more than to that
of party; the second time, ten years later, he had
lost it purely to party interest. In 1711 court wits
could still jest that Kent thought himself "the head
of the Whigg Party." 1 "' But when power came to be
identified more with politics than position, Kent
parted company with political men like Walpole.

With that attitude Kent was akin to his third
son-in-law, Lord Charles Cavendish, and to his
grandson Henry Cavendish. They, too, sought and
found "consequence" along paths other than
political. In their choice, science, they found
opportunity to exert their Devonshire legacy of
political principle.

111 18 May 1725, HCJ 20:536.

,,4 C»rcat Britain, Historical Manuscripts Commission. Report on
the .Manuscripts of the Earl of Egmont Diary of Viscount Percwai
Afterwards First Earl of Egmont. Vol. 1: 17.10-1 733 (London: His
Majesty's Stationery Office. 1920). 189, for example. In August of
1732 Kent was at "a great Court, being Council day" and was
"saluted" by Kgmont. Walpole. and other chief ministers. Ibid. 1:290.

I'SThe duke of Kent to Robert Walpole. 15 Dec. 17.«. in
Plumb, Wa/poJe 2:297.

'"•The W'enlworth Papers, 219.

Copyiighied maeti

PART 2

/ord Charles Cavendish

Copy lighted malarial

CHAPTER 1

Politics

Early Years and Education

Lord Charles Cavendish was born in July or
August of 1704.' He joined three sisters and two
brothers in the nursery of William and Rachel
Cavendish, Lord and Lady Harrington. At least
three more girls and one more boy were born into
the family in the next few years; Charles grew up
probably not very much noticed in the middle of
his siblings.

When Charles was three, his paternal grand-
father, the first duke of Devonshire, died, and his
father took possession of the title and of the
extensive properties of the Devonshires. The new
Devonshire House at Piccadilly, the grand house at
Chatsworth in Derbyshire, Hardwick Hall in
Nottinghamshire, and several other houses could
now all be called home by the Cavendish children,
even if they did not live in all of them. For a while
their homes also included Southampton House, the
London residence of their maternal grandmother,
Lady Rachel Russell. They visited the homes of
their other Russell relatives, particularly Woburn
Abbey in Bedfordshire, their mother's girlhood
home, Stratton House in Hampshire, their grand-
mother Russell's country estate, and Belvoir Castle
in Leicestershire. 2

We pause to consider the architectural
setting into which Lord Charles Cavendish was
born, and which he would have taken for granted
as rightfully /lis. Lord Charles coincided with the
great age of English domestic building, the
enthusiasms of which did not play themselves out
until the end of his son Henry's life. The moving
of earth and the piling of stones were ubiquitous
sounds of the gentle English landscape in this
period. By whatever manner the aristocracy and
their imitators managed to raise money, they knew
what to do with it: build, expand, and then rebuild.
On the same scale as their palaces were the parks
they set them in, with their artificial lakes,
waterfalls, forests, and picturesque details such as

villages (or their removal). Servants came cheap
and were employed at these houses in numbers far
beyond what was needed to keep them running.
The public display expressed the raison d'etre of a
caste: wealth, power, and title. Ostentation
sometimes led a peer to ruin but in a good cause,
since overspending on developing an estate was
not regarded as a disgrace. The Devonshires did
not overreach, but they did not hold back either;
they simply got richer with each passing
generation, and as they did, they added more
rooms and filled them with more statuaries and
libraries and gilt. 3

Devonshire House in London was rebuilt
for the third duke of Devonshire by William Kent
in 1733. Likened by an unfriendly critic of the time
to an East India Company warehouse, its exterior
was indeed plain, but that together with the rich
interior could be taken as a kind of family portrait
of the Cavendishes. 4

Chatsworth, the family house in Derbyshire,
with its splendid rooms kept in readiness for visits

'We deduce his probable birtbdate from several facts: he
became a member of the House of Commons in 17.25, and the
standard practice for the son of an aristocratic family was to enter an
election right after his majority. ( Corresponding to the assumption
that he was therefore born in 17(14, we have a remark in a letter by
the duchess of Qucensberry to Lady Harrington, Lord Charles's
mother, dated 4 July /1 704/, Devon. Coll., no. 94.1: "I believe before
now the wedding is over in your family and 1 hope the next news we
hear from it will be your having follow'd my example in bringing a
son," which suggests that Lady Harrington was expecting a child
soon. The order of births of the other (Cavendish children, for some
of whom the birthdates are known, make an earlier date not very
likely. Neither docs the fact that Charles received independent
means of support from his father only a week before his election to
Parliament in April 1725, since if he had been 21 already, he would
have already been receiving a regular annuity. Devon. Coll., 1-/19/31.

2 Lois C. Schvvoerer, Lady Rachel Russell, "One of the Rest of
Women" (Baltimore: The Johns Hopkins University Press, I9XK), 222.
Schwoerer lists the Russell family homes and refers to Lady
Russell's closeness to her children. Various family letters from this
period and later refer to members of the family visiting one another.

'J. H. Plumb, Men iin/i Centuries (Boston: Houghton Mifflin,
1963), 69-70, 74-75, 79.

J Hcrmionc Hobhouse, Lost London (New York: Wcathervane
Books, 1971), 29.

Cavendish

by the royalty, held, and still holds, pride of place
among the Devonshire properties. The first duke
of Devonshire made great additions to the existing
Tudor house as a testimony to two inseparable-
facts: his own greatness and the successful outcome
of the Glorious Revolution. The interior of the
redone house and the gardens outside it were
inspired by Versailles (the duke instinctively hated
Louis XIV but saw no contradiction in emulating
his taste), but the feature for which the house was
most famous was probably not the lofty ceilings
painted with scenes of classical mythology but the
ten or more flush toilets. 5 These unlikely conve-
niences were a touch of modern practicality, which
we imagine made a technical impression on young
Lord Charles Cavendish.

The next frenzy of rebuilding at Chatsworth
left the house pretty much as it was but totally
transformed the park. The fourth duke of Devon-
shire brought in the great landscape gardener
Lancelot "Capability" Brown to remove the
Euclidean geometry of the first dukes version of
the gardens of Versailles and to replace it with the
type of English garden that was then coming into
fashion, one not set apart from the natural
landscape but arranged in harmony with it. The
Swiss scientist Horace Benedict De Saussure
visited Chatsworth in the 1760s, after the fourth
dukes changes, and called it a "fairy palace in a
beautiful wilderness."'' With its acres of lawns and
clusters of elms and oaks, this was the park
described by Jane Austin. The new response to
nature coincided with Henry Cavendish's entry
into the world of science. Unlike Lord Charles,
Henry did not live at Chatsworth, so far as we
know, but he was certainly familiar with it from
visits. The two superposed styles of the Chats-
worth park, which might be called the geometrical
and the natural, would seem to prefigure Henry
Cavendish's calling.

Chatsworth would undergo other major
changes, such as the landscaping of Joseph Paxton,
who went on to design the famous, prefabricated
glass-and-iron Crystal Palace for the 1851
international exhibition in London, but to describe
these would take us beyond our subject. To this
day, Chatsworth House reveals to the world the
good sense of the rebuilding undertaken by the
first duke of Devonshire, a respectable amateur
architect. The good sense did not belong to that

extravagant man so much as to the architecture he
inherited. For all of its grandeur, the house has the
harmonious proportions and classical elegance of
the period. What Lord Charles and his son Henry
seem to have extracted from the material setting of
their family was the core of reason expressed in the
graceful architecture.

In Henry Cavendish's day, as today, the
great country houses of the nobility were semi-
public tourist stops. There was, as the tourist
Saussure said, a fairyland quality about Chatsworth,
for it was only fifteen miles from Sheffield, a rising
industrial center. The owner of Chatsworth, the
duke of Devonshire, was also the very sensible-
owner of income-producing mines. In its best days,
the duke's copper and lead mine at nearby Eeton
brought in 30,000 pounds a year. Two hundred
fathoms deep, a Boulton steam engine worked it
from the top, a tourist noted. 7

Inside their substantial four walls, in town
and in the country, the Cavendish family enjoyed
warm, informal relationships. Unlike many another
aristocratic family, for example, the duke of Kent's,
Charles's family did not use their formal titles for
one another. In their letters, even after they were
adults, Charles's sisters referred to their mother as
"mama," not "her Grace," the title appropriate for a
duchess, and they wrote of "brother Charles" rather
than "Lord Charles" and of "Granmama Russell"
rather than "Lady Russell." Charles's sister
Elizabeth looked back with sadness on their
childhood when, in 1721, after the deaths of their
eldest sister, Mary, and their youngest brother, John,
she wrote to another brother James abroad about
Charles, who was about to join him: "It was some
comfort to have one of you, but when both are gone
I shall find /a/ great change when I consider I was
once happy in y c ' company of so many brothers and
s s ; but it is a thought I cannot bear to think of."*

''John Pearson, The Serpent and the Stag... (New York: Holt.
Reinhart and Winston. 1983). 73-79.

'■Douglas VY. Freshfield and I I.I". Montugnia, The Life of Horace
Bin/diet De Saussure (London: Edward Arnold, 1920), 114.

'The tourist was Henry Cavendish's colleague Charles Hatched,
w hose "expectations" for Chatsworth were disappointed. The Halrhelt
Diary. A lour through /he Counties of England and Scotland in I7V6 Visiting
Their Mines and Manufactures, ed. A. Raistrick (Truro: I). Bradford
Barton, 1967), 64-66.

"Lady Elizabeth Cavendish to Lord James Cavendish, 13 Feb.
/1721/ and 24 April /1721/, and Lady Rachel Morgan to Lord James
Cavendish. 26 September/ 1723/. Devon. Coll., nos. 166.0, 166.1, and
167.0, respectively.

Politics

Of his siblings, two brothers, William and
James, and four sisters, Mary, Raehel, Elizabeth,
and Anne, survived into adulthood with Charles.
Their earliest education was probably under the
care of tutors and governesses. Their grandmother
Lady Rachel Russell, who on her mother's side was
of Huguenot origins, in the 1680s had advocated
using the French refugees as tutors. 9 Later, she
entertained some negative views of the instruction
offered by French tutors, but she nevertheless took
considerable trouble to find a French tutor for her
grandchildren by another daughter. 10 The Caven-
dishes may have followed her advice, too, espe-
cially since the whole family continued the close
connection with their Ruvigny relatives, now
settled in Greenwich and parts of Hampshire." At
any rate, when James and Charles toured the
Continent in 1721-24, they did so under the care
of a Frenchman, a Mr. Cotteau. 1 ' The Cavendish
daughters were educated to interests as com-
monsensical as their brothers. On her honeymoon,
Rachel reported to her brother James on a visit to
the Derby silk mills, "thought to be one of the
finest inventions that ever was seen of the kind." 13
Elizabeth was even more impetuous and indepen-
dent than Rachel, if we can judge from her few
letters. Seeing her life as "idle," she wrote to
James: "I only wish I was your brother instead of
your sister and then I would have bin partaker with
you in your travels." Forced to remain behind, she
informed her brothers of the politics of the day.
Looking at it from the heights of her fathers
positions in the House of Lords and in Walpole's
government, she approved of a minister who did
not enrich himself by his office, and she reported
the birth of a prince causing "very great" joy
amongst the people as a political advantage, the
birth coming "very seasonably to stir up ye spirit of
loyalty in y* people who are in a general
dissatisfaction with y e king and parliament who
they think don't go y c way to redrys their grivances
caus'd by y e south sea." 14 There are no girlish frills.
The Cavendish boys received only the beginnings
of their education at home. Their grandmother
Lady Rachel Russell was of the opinion that "our
nobility should pass some of their time" at a
university; "it has been for many years neglected." 15
The view was shared by her daughter and son-in-
law Devonshire who sent their eldest son, William,
the first to attend a university, to Oxford in 1715,

when he was sixteen, entering him at New Col-
lege. As a member of a whig family in a tory
citadel, William joined with others of whig persua-
sion, only to find their group the target of the mob.
Two months later, in 1717, he was granted the
degree of Master of Arts and left Oxford. The
family biographer comments on how quickly a
duke's son could attain that degree; considering
Cavendish prudence, which was an especially
characteristic trait of his parents, Lord William's
political adventures and his leaving Oxford may
not have been unconnected."' Lord James and
Lord Charles in any case were not sent to
a university.

They began their formal schooling at Eton,
where they were entrusted to Dr. Andrew Snape,
headmaster from 1711 to 1720, on the recom-
mendation of Robert Walpole, their father's friend
and political ally. In 1718, for which there exists a
"Bill of Eton Schole," Charles, then fourteen, was
in the fifth year, a grade in the Lower School
known as Lower Greek. James was two years
ahead of him. 17 Neither boy finished the entire
course, which for Charles would have required

''Mary Berry, Some Account of the Life of Rachael Wriothes/ey Lady
Russell, . . . Followed 'by a Series of I stlers . . . . (London, 1819), 73.
'"Schwoerer, Lady' Rachel Russell, 227.

"Ibid., passim. Samuel Smiles, The Huguenots: Their Settlements,
Churches, anil Industries in England and Ireland (New York. 1868), 208-
11,314.

,2 Rachel Cavendish, duchess of Devonshire, to Lord James
Cavendish, about 1722, 20 March, 12 July, and 11 Nov. 1723, and
13 Feb. 1724. Devon. Coll., nos. 30.10, 30.1 1, 30.12, 30.13, and 30.14,
respectively.

"Lady Rachel Morgan to Lord James Cavendish, 26 September
/1723/.

,4 Lady Klizabeth Cavendish to Lord James Cavendish, 24 April
/1721/.

ls Lady Rachel Russell, Letters of Lady Rachel Russell; from the
Manuscript to the Library at Wohurn Abbey. . . . 5th cd. (London,
1793), 550.

"•Joseph Foster, Alumni Oxonieuses: The Members of the University
of Oxford, 1715-1886. . ., 4 vols. (London, 1891) 1:231. Francis
Bickley, The Cavendish Family (London: Constable, 1911), 189-90.

I7 R. A. Austen Leigh, Eton College Lists 1618-1790 (Eton
College: Spottiswoods, 1907), xxiv-xxvii, 14-18. J. H. Plumb, Sir
Robert Walpole. Vol. 1: The Making of a Statesman (London, The
Cresset Press, 1956), 253. II. C. Maxwell Lvtc. A History of Eton
College 1440-1884 (London. 1889), 286-87. The "lower master" of
the lower school in 1718 was Francis Coodc, who held that position
from 1716 to 1734, succeeding Thomas Carter. There were four
lower school assistants that year, Thomas Thackeray, Adam Elliot,
John Burchett, and Charles Willats, most of whom were drawn from
King's College, Cambridge, but Burchett was from Peterhouse. Eton
College Lists, xxxv. It was customary at V.wn for the "sons of wealthy
persons to have private tutors," who were not the same as the
assistant masters. Lyte, History of Eton College, 4th ed. (London,
1911), 284.

Cocyrighied malarial

Cavendish

another five years. By 1721 both were heading in a
direction other than the university, for which they
probably were not prepared in their knowledge of
ancient languages in any case. Young noblemen, as
the advice given to the father of one of them in
1 723 shows, had other options: "Tho' he does not
ply his book close," this father was told about his
son, it may not proceed from the want of capacity
and inclination

but rather from his studying in the dead
languages, which he has not been well grounded
in. I have knowen sevcrall instances of this and if
it be the case or perhaps his being too much
indulged in sloth when younger, I do not see why
either of them should be a reason for breaking off
his studies. 1 le can read in Italian and French
most of the things that are necessary for a
gentleman, and tho' he should not give a very
close application, something usefull will stick; and
who knows but by degrees he may come to like
what he now has ane aversion to. Were he mine, I
would make him spend some time at Geneva in
the studie of the law, should it be only to keep
him from being imposed upon by pettyfoggers.
Historic and geometry are accomplishments fitt
for a gentleman and surely he can never serve his
country or tamely without knowledge, and
geometry, if he give in to it, will at all times be ane
amusement when he cannot be more profitably
imploy'd. When he has made a tolerable progress
in these, it will not be amiss that he make a tour in
I*' ranee and Italy that he may learn from
observation w hat he has not gotc by reading.'*

The reference was to the by now obligatory
grand tour that began in France, perhaps passed
through Holland and Switzerland, and then settled
down to a residence in Italy, home of Rome and
the Renaissance. No Knglishman could pretend to
an education or any degree of sophistication or any
defense against a sense of inferiority without it.
Two or three years abroad were the rule, a just
compensation for having been born in backwater
England. 1 '' Some formal study might be combined
with the sightseeing and cultural exposure. Lords
Anthony and I lenry de Grey, the sons of the duke
of Kent and the brothers of Lord Charles's future
w ife, Lady Anne, had followed this course several
years earlier. Now their sons were doing their duty:
in 1716 Lord I lenry was planning to go to Geneva,
and Lord Anthony sent him advice from Venice:

Att Geneva you will find several persons that will
be very helpful to you I don't doubt, and I shall
send a letter or two to some of the best I knew
there who are of the best familys, men who arc-

pretty well acquainted with the world and whose
conversations will be agreble as well as instructive,
that shall wait upon you and do any service that
lies in theit power as soon as ever you arrive: there
are like wise some of the young men I was
acquainted with who will be ready enough to
introduce you into any other company you shall
like or care for. I suppose you intend to study a
little of the Civil Law there; the petson I had and
who is accounted one of the best is Mr Guip a
diligent and Studious man and likewise
understanding in History and Chronology.

Having followed his own stay at Geneva by
travels in Italy, Lord Anthony displayed in the
remainder of his letter that he had profited from
the lessons in history and become a careful
observer of "antiquities." 20 Lord James Cavendish,
whose later exploits suggest an early interest in
horsemanship and an active life, was probably, and
quite appropriately, intended for the military. By
1721, he had gone from Eton to the "Academy" at
Nancy and then Luneville in Lorraine. Lord
Charles was then about to join him, and two years
later he was writing to his mother from Geneva. 21
I Ience there is the likelihood that both places
contributed to his education.

The "academie d'exercises" at Nancy, the
capital of Lorraine, had been established in 1699,
soon after Lorraine had been taken back from the
French and reconstituted a duchy by the Treaty of
Ryswiek of 1697. Although the dukes of Lorraine
were allowed no army of their own, their military
academy attracted young foreign aristocrats, some
carrying "the greatest names of Europe." By 1713
the academy had added a course in public law to its
curriculum, and Duke Leopold himself established
one in natural law. The academy had the purpose
of educating the cadets for the court guards, the
only military body (aside from a civilian militia)
still remaining to the dukes, creating a close
association with the court, which affected its
location. In 1702, for example, at the start of the
War of the Spanish Succession, the French had

'"Great Britain. Historical Manusc ripts Commission. Report OH the
Manuscripts of Lor// Polwarth, Preserved at Mnioiin House, liemrirkshire,
vol. .5 (London: His Majesty's Stationary Office, ). 287-88.

"Plumb, Men and Centuries, 55—60.

-'"Anthony dc (ircy, carl of Harrold, to Lord Henry de Grey,
about 1716, Bedford County Record Office, Wrest Park Collection.
L30/5.

-'Lady Elizabeth Cavendish to Lord James Cavendish, 13 Feb.
and 24 April / 1 731/. Rachel Cavendish, duchess of Devonshire, to
Lord James Cavendish, 11 Nov. /1 723/.

Copy rig hi ea

Politics

reoccupied Nancy, forcing Leopold to withdraw
with his court to his castle at Luneville, a building
then too ancient to be suitable for an eighteenth-
century ducal residence. Leopold replaced the old
structure with a large, new residence, which
gradually became the official capital of the dukedom
even after Nancy had been freed of the French
again in 1714. In 1719 a fire temporarily set back this
development by destroying the ducal apartments
at Luneville, apparently forcing the court back to
Nancy for a short time. It was during this period
that Lord James Cavendish joined the academy.
Duke Leopold, seeing an opportunity for further
building, added a "cabinet des herbes" to his
Luneville residence, a good library, and a physical
cabinet. Under the influence of Newton's physics
and determined to do his own experimenting, he
constructed some of the necessary instruments
himself and bought the rest, a beautiful and
expensive collection from London. In the spring of
1721, just before Lord Charles joined his brother in
Lorraine, the duke moved his military academy
from Nancy to Luneville,-- bringing it into the
immediate neighborhood of the scientific facilities
he had assembled there.

I ,ord ( lharles ( lavendish left I ,ondon tor his
education and tour abroad in March 1721, undoubt-
edly with another party traveling to Paris, since he
was to be met by his brother Lord James's valet
there, and as the seventeen-year-old son of a duke
he would not have been sent off alone. 2; Expected
to be with James by mid-April, he instead stayed
on in Paris for three weeks longer than planned. As
Lord Anthony de Crey had informed his brother a
few years earlier, at Paris there were "many things"
to be "observed."

You will not stay long there perhaps the first time
only see a little of the Town. . . . You wont ommitt
however the sight of the most principal things, as
the Louvre, the Tuilleries, Place Vendosme &
Victoirc, Place Royal, the Luxemburg, the Church
of Notre dam, L'hotel des invalides, Versailles,
Trianon. . . . 24

Both his initial visit to Paris and his and
Lord James's stay there for several months in
1723-24 came at a favorable stage in English-
French relations, during the regency of the duke of
Orleans and immediately after. The friendly
climate toward England at court was accompanied
by a resurgence of cultural life in Paris as, following
the death of Louis XIV in 1715, the French

aristocrats returned from Versailles to Paris.- 5 The
flourishing arts, operas, theater, and other
entertainments lured so many of the British to
Paris in these years that the resident at Paris,
Thomas Crawford, complained in 1723 that "we . . .
should have had the halfe of the people of
England" there if it had not been for the unsafe
conditions of the roads; "this town began to be full
of London apprentices that came running over
here with their superfluous money instead of going
to Tunbrige," an English resort.-' 1 The regency was
also marked by another interest of the duke of
Orleans, much closer to Lord Charles's eventual
concerns; this was the duke's interest in the natural
sciences and his attention to the "improvement of
the implements and appliances of the mechanical
arts." 27 Rene Antoine Reaumur, the regent's
protegee at the academy, published his important
study of the iron and steel industry in Paris in 1722,
which may well have come to Lord Charles's
attention, given the practical bent of his family and
their ownership of Derbyshire lead mines. 28 As a
Cavendish, he may have enjoyed even more direct
exposure to the Parisian scientific world, but we
have no evidence for that.

After about a month in Paris in 1721, if he
proceeded as planned, Lord Charles joined Lord

22 Michel Parisse, Stcphane Gaber, and Gerard Canini, Grandes
Dates rle UHistoire Lorraine (Nancy: Service des Publications de
I'l 'nivcrsitc de Nancy II. 1 0«2 ). 43 Michel Antoine. "La cour de
Lorraine clans I'Kurope des lumieres." 69-76, and Claude Collot.
"La faeulte de droit de I'l "nivcrsitc de Pont-a-Mousson et de Nancy
an XYIIP siecle," 215-26, both papers in La Lorraine Hans /'Li/rope
des lumieres. Aries ttu colloi/ue organise par la Faeulte ties lellres el des
sciences hunmines de I'l 'nivcrsitc lie Sana, Sana. J4-J7 octobre 1966.
Series Annates de t'Esl. Menioire 34. (Nancy: Faeulte des lettres er
sciences humaines de I'l "niversitc, 1968), 70—72, 218. Edmond
Delorme, Luneville et son arrondissement (Marseilles, Lafitte Reprints.
1977). 3. 17. 18, 111. Pierre Boyc. Les Chateaux flu Roi Stanislas en
Lorraine (Marseille, Laffitte Reprints, 1980), 3-4.

2 -'Lady Elizabeth Cavendish to Lord James Cavendish, 13 Feb.
/1721/. One party bound for Paris that Lord Charles might have
joined was that of the English ambassador in France, Sir Lucas
Schaub, a young man of thirty-one, who was to leave London for
Paris on 23 I-'eb./7 March. That plan, given that the trip took four to
five days if all went smoothly, would have put him in Paris in the
second week of March, the time when Lord James was to send his
valet to meet Lord Charles. In the event, Schaub did not leave
London until March 1/12, which may account for the delay in Lord
Charles's plans, too. Manuscripts of Lord I'olwarth 3:49, .S2.

- 4 Anthony de Grey, earl of Uarrold. to Lord Henry de Crey.
about 1716.

:s James Brcck Perkins. France under the Regency with a Review of
the Administration of Louis XIV (Boston and New York. 1892). 374-96,
554-57, 559-62.

'-'•Manusiripts «/ I .ord I'oharth 3:309.

-'Perkins. France under the Regency, 556.

-"J. B. Cough, "Reaumur, Rcne-Antoine I'erchault de," D.S/i
11:327-35, on 328.

('. tree n dish

James at Luneville. For nearly two years after that,
until late in 1722 or early in 1723, Lord Charles's
activities and whereabouts can only be con-
jectured. Given the pattern of his brother's stay
abroad, Lord Charles may very well have spent a
year at Luneville. During the winter of 1722-23,
the brothers, together with a tutor, were traveling,
probably in the south. James had been tempted
into gambling, prompting his mother to point out
to him that the "right use" of their travels should
be "seeing what is most curious in y L ' places you
pass thru & making y r observations upon 'em."
The following March, James was staying with a
prince and princess, an "expensive enuff" way of
life, as his mother comments, discussing his
allowance. Neither the duchess's letter to James in
March nor another one in the middle of July refer
to Lord Charles, making it likely that Charles
spent some time on his own at Geneva, from where
he had written to his mother that summer or fall. 29

The Academic de Calvin in Geneva had
attracted not only the sons of the duke of Kent, but
the sons of several great English and Scottish
families, including the Cavendishes. In 1723, four
professors at the academy offered courses in civil
and natural law and in philosophy, including,
apparently, natural philosophy, since one of its
students, the later mathematician Gabriel Cramer,
had only recently completed a thesis on sound and
would the next year compete for the chair of
philosophy, receiving a share in the chair of math-
ematics instead, with the assignment of teaching
algebra and astronomy. ,(l If Lord Charles did not
meet Cramer at the academy that year, he may
have become acquainted with him through
Cramer's brother Jean, the new professor of civil
and natural law, only twenty-two at the time himself.
At any rate, when Gabriel Cramer visited London
sometime in 1727-29, he was easily received into
the circle of mathematicians and Fellows of the
Royal Society connected with Lord Charles."

In November of 1723 Lords James and
Charles Cavendish were together again, having
only just arrived in Paris. Their stay in France
required a doubling of their allowances, each now
getting £100 annually, and advice about greater
caution on the roads: "be very carefull now you are
in France," their mother w rote, "how you travel, &
also of being out late in y c ' streets w^ they tel me is
very dangerious, murthers being there soe

common." 32 They spent the winter there, still
under the care of Mr. Cotteau, with their mail
reaching them through the banker Jean Louis
Goudet. In February 1724 when the end of the
their tour was in sight, they appealed to their
parents for a few months more. "Relating to y r
return into England," the duchess wrote,

I believe y' father in that wo'd be willing to do
what he thought was most agreeable to y r own
inclinations, Mr Cotteau writs word you imploy y r
time so well, that he thinks it might be for y'
advantage if you stay'd in France some months
longer, but in y' next you may let me know what y
own thoughts are, y r coming back by Holland is
what I believe my L d designes if you like it.- 5 - 5

Charles and James had their way. They also
followed their father's plan of returning home by
way of Holland, a detour that very nearly cost
Charles his life. On 24 September that year, in
"blowing Stormy weather," Captain Gregory of the
Katherine Yacht at Ostend

about Three in the afternoon was unhappily
Surprized by a Passage Boat oversetting just under
my Stern, in which were Two of his Grace the
Duke of Devonshire's Sons, viz the Lord James
and Charles, with their Governor and Servants,
who by the assistance of my People were all most
miraculously Saved, particularly Lord Charles,
who Sunk under my Counter, and was carried by a
vers' Strong Tide between me and another Ship

"'Letters from the duchess to Lord James Cavendish above.

"'Charles Borgcaud. Histoire de I'Vnivenitf de Geneve. I'.Academie
de Calvin 1559-1798 (Geneve: Georg, 1900), 442, 641^12. According
to the registers of students, the Cavendishes who attended the
Geneva academy were Charles Cavendish's great-grandfather
William Cavendish, who was accompanied there by his tutor Thomas
Hobbcs, the philosopher, and Charles's grandfather William
Cavendish, the later first duke of Devonshire. However, the registers
are not complete, particularly not on foreign noblemen, who might
have stayed in Geneva only a few months. Anthony de Grey, earl of
Harrold. who studied law in Geneva for a while, for example, does
not appear in the register: the absence of Charles's name there is no
indication that he did not attend the academy or study with a private
teacher in Geneva for a while. Sven Stclling-Michaud and Suzanne
Stelling-Michaud, cds.. I.e Litre du Recleur de I'Academie de Geneve,
vols. 1-3 (Geneva: Droz. 1959-72). On the registers: Michael Heyd,
Fietween Orthodoxy and the Enlightenment. Jean-Robert Chouet and the
Introduction oj Cartesian Science in the Academy of Geneva (Boston:
Martinus Nijhoff, 1982), 245-47.

"Cramer and Lord Charles Cavendish were exact contemporaries.
Cramer's travels were a part of his appointment at Geneva and
intended for his further education. The scientists he met in England
included Nicholas Satinderson, Hallcv, Sloane, De Moivre, and
Stirling. Phillip S. Jones. "Cramer, Gabriel," DSB 3:459-62, on 459.

'-Rachel Cavendish, duchess of Devonshire, to Lord James
Cavendish, 11 Nov. /1 723/.

"Rachel Cavendish, duchess of Devonshire, to Lord James
Cavendish, 13 l-'eb. /1 724/.

Copyrighted maeri

Politics

under water, till he got as far forward as my Stern,
where he arose, and got hold of my Shoar fast,
from whence we Saved his Lordship, though
almost Spent.

Lords James and Charles had been on their
way to Calais, which suggests that they were
coming from The Netherlands, probably The
Hague. After losing "most of their Baggage and
Apparel, except w hat they had Ordered to Calais,"
in the accident, the Cavendish brothers decided to
stay with Captain Gregory for the crossing. The
captain's report of the accident reached their father
by courtesy of the admiralty on 5 October. 34 Lords
Charles and James undoubtedly followed close
behind, Charles having been abroad for three and a
half years.

House of Commons

Technically speaking, despite his courtesy
title (although courtesy, the title was not optional),
Lord Charles Cavendish was a commoner, but he
was nevertheless a member of the highest circle of
the British aristocracy, and as such he had been
brought up to the values of the aristocracy, which
included the principal one of "duty of service." 35
To a member of the aristocracy, especially at the very
top, the only acceptable form of occupation (aside
from administrating, but definitely not farming, his
property) was public service, usually in government
or in the military. It came down to a narrow but
attractive choice of occupations. The Cavendishes
had served in some of the highest offices at court and
in the government for almost half a century, and
Lord Charles Cavendish followed suit as soon as he
reached maturity by becoming a member of the
House of Commons at a by-election in the spring of
1725. Other interests, in the arts, architecture, belles
lettres, various areas of scholarship, or natural
science, no matter how expertly pursued, had to
keep the outward appearance of an aristocrats
private indulgence, at best to be shared with friends.
To carry out any such work to earn money or
recognition, that is, in the case of scholarship and
science, to publish the product of one's work for
income, for someone of Lord Charles Cavendish's
rank would have been out of the question.

The occupational limitations that British
society imposed on its aristocrats guided Lord
Charles Cavendish's work in science (and probably
determined his reputation as a scientist, or rather

the lack of it). For many years he carried on
scientific investigations that were valued and used
by other scientists — he even won the Royal
Society's Copley Medal — but as befitted someone
of his rank, he published nothing except the one
piece of work for which he received the prize. But
he could and did contribute publicly to science in
the same manner in which he had served in
government, as a "parliamentarian" of science: as a
member of the Royal Society, on its councils and
committees, and on the boards and committees of
other institutions. He became one of the most
important of the official representatives of science
of his time in Britain and its untiring servant; he
achieved that by scientific talent, practical ability,
and long parliamentary experience, and not least of
all also by being a Cavendish.

Lord Charles Cavendish is a good example
of a kind of scientific practitioner who played a
useful role in eighteenth-century British science
but did not survive into the later professional
organization of science. He also offers us the
understanding of science that he himself arrived at,
which was a general and new understanding of the
time; namely, that science was becoming an area of
public concern, with an increasing number of
connections to practical problems; he took this
understanding futher, seeing in science an activity
of sufficiently general importance to constitute an
appropriate area for the service of an aristocrat.

When Lord Charles Cavendish took his seat in the
House of Commons as Member of Parliament for
Heytesbury, Wiltshire, in the 1725/26 parliamentary
session, 36 he joined there all but two of the adult
males of his immediate family: his eldest brother,
Lord Harrington, his uncle Lord James Cavendish,
his two brothers-in-law, Sir Thomas Lowther and
Sir William Morgan, and a first cousin. The two
exceptions were his father, who as duke of
Devonshire sat in the House of Lords and was then
lord president of the privy council, and his brother
Lord James Cavendish, who was in the military.

"J. Burchctt to William Cavendish, duke of" Devonshire, 5 Oct.
1724, with the enclosure of a "Copy of a Letter from Captain
Gregory of the Katherine Yacht to M' Burchett dated the 25* of
September 1724 0. S. from Ostcnd," Devon. Coll., no. 179.0.

!5 John Cannon, Aristocratic Century. The Peerage of Eighteenth-
Century England (Cambridge: Cambridge University Press, 1984), .54.

i6 Romncy Sedgwick, The House of Commons 17/5-1754, 2 vols.
(New York: Oxford University Press, 1970) 1:536.

Copyrighied malarial

Cavendish

putting off his brief stint in the Commons by
fifteen years, until just before his death. Lord
Charles Cavendish could have had no doubt about
what was expected of him. (To get a proper picture
of the inevitability of that particular blueprint for
an aristocrats life it should be noted that except for
his uncle. Lord C Charles and his relatives in the
Commons were all under thirty, he being the
youngest then at twenty-one.) This dense
representation in the Commons of an aristocratic
family such as the Cavendishes was only partly due
to politics; beyond his father's close association
with Robert Walpole, the head of the current whig
administration. Lord Charles was in the Commons
as a representative of his family's private interest.
Very suitably, therefore, he made his first
appearance in the Journal of the House of
Commons in April of 1726 in connection with a
private bill (which we discuss below), drawn up by
his brother, concerning the estate of his brother-in-
law Sir Thomas Lowther.

During the years 1725— 11, the period Lord
Charles Cavendish was to spend in parliament, the
Commons had 558 members who met usually in
the second half of January and remained in session
usually until May or June, the precise beginning
and end of each session being subject to political
manipulation by the administration. Attendance —
the Commons met five or six days a week, usually
from around the middle of the day until late
afternoon and at times late into the night — was
similarly a matter of politics: usually fewer than
half of the members attended, but for important
issues the House had means of coercing
attendance, tactics that were more easily brought
into effect by the party in power, which by this
time could elect one of its own speaker of the
house, than by the opposition. With an acceptable
excuse, a member could avoid attending the House
altogether. 57

The business of the Commons divided into
three parts. First, the House had the "public" tasks
of levying taxation and supplying the government
for its operation and for the military; of considering
foreign policy (which was the monarch's prerogative
but took up much of the Commons' time, anyway);
and indeed of acting on every public issue the
administration or other members chose to put
before it. The second task of the Commons, in
importance if not in order of attention, for it was

always taken up before anything else, was to hear
grievances concerning the privileges of the
members of the House and concerning election
improprieties. The third task of the Commons was
the enactment of so-called private bills. They
would more appropriately have been described as
bills of local — as opposed to national — concern.
These bills, which covered everything from road
and canal building to labor disputes and
manufacturing regulations to legal settlements of
private estates, took up less time than the national
issues in the sessions of the whole House, but they
did require extensive committee work. They were
assigned to select committees usually of between
thirty and sixty members, first to consider the
petition for legislation on the matter, and then to
draw up and discuss a bill before the House voted
on it. Having the right to conduct hearings, the
committees brought in witnesses and material
evidence. They met when the House as a whole
was not in session, unless the committee was
constituted of the whole House, in the mornings, for
example, often for several weeks, greatly extending
the hours of attendance to the parliamentary duties
of a conscientious M.P.- W

Civen that Lord Charles Cavendish was so
very young, completely inexperienced, and rela-
tively unknown (more than once in those early-
years he was mistaken for his brother James, who
was older but not as serious a young man), it is not
surprising that he entered only slowly into the
work of the Commons. Re-elected in 1727, but
from the large constituency of Westminster instead
of small Heytesbury, w his involvement in the
House's activities immediately picked up in 1728
and 1729, only to be followed by four years of
personal problems arising especially from his wife
Anne's struggle with tuberculosis that kept him
away from his duties much of the time. When, in
1733, his wife died, Cavendish immersed himself
in his duties in the Commons.

In his first years there, Cavendish was often
brought into committees by members of his family
on family matters, the natural way for him to be

,7 R D. (>. Thomas, The House oj Commons in the Eighteenth Centun
(Oxford: Clarendon Press. 1971). 2, 92, 123-26, 157-57.

'"Thomas, House of Commons, 13. 45-46, 51-59, 264-70.

"Sedgwick, House 1:285. 21 July 1727, St. Margaret's Vestry.
Minutes 1 724-1 733. Westminster City Archives, K 2419.

Politics

introduced to committee work. His family first
enrolled his services in March 1726, in a case that
would benefit his sister Lady Elizabeth and her
husband Sir Thomas I >owther. Here is how it went.
Lowther had petitioned the Commons that his
family be granted the inheritance of Furness
monastery in Lancashire, trying to establish
permanently an old family claim. Lord Charles
Cavendish's brother Harrington was ordered, along
with two others, to draw up a bill to that effect,
which was then handed over to a committee that
included all the Cavendishes in the House,
including Charles. The bill was passed, and as was
the custom, the chairman of the committee,
Harrington, was ordered to carry it to the House of
Lords for their "concurrence." When two weeks
later this still had not been done, Lord Charles was
sent to the Lords with it in his brother's place. 40 In
1727 he was on a committee approving a bill from
the House of Lords settling estate matters for the
daughters of Elihu Yale, one of whom was married
to his uncle Lord James Cavendish; 41 in 1729 he
dealt with the selling of two parts of the manor of
Steane, the duke of Kent's property and therefore a
matter having to do with the inheritance of Lord
Charles Cavendish's wife, Lady Anne; 42 in 1730 he
dealt with an estate sale for his brother Lord James,
who needed money to pay gambling debts. 43 Even
more distant relatives could claim his support on
committees: he was involved in settling the estate
of one Thomas Scawen, 44 for example, the
husband of his mother's first cousin, or in the legal
change of name of two of his Manners cousins. 45 In
1736 his relatives could serve him in turn, when he
sold the Hertfordshire estates he had bought
shortly after his marriage as an investment of his
wife's dowry and as a country seat for his family. 4 ''

In the spring of 1726, Cavendish was
involved in work on a private bill that offers us a
good example of a family matter which is also of
public importance. 47 It was also Cavendish's first
parliamentary exposure to certain technical
problems. The bill was the latest of a long series of
parliamentary acts beginning in the seventeenth
century providing for the draining of the Bedford
Level fens, over 1,600 square miles of marshland to
the south and west of The Wash in eastern England.
In the seventeenth century, Francis Russell, fourth
carl of Bedford, and his son and successor William,
later first duke of Bedford (Lord Charles Cavendish's

direct ancestors), had organized about eighty
landowners into a corporation of "adventurers" to
finance the draining of these plains, which were
still common land, in return for 83,000 acres of the
resulting farmland. The Russells and their adven-
turers undertook also to maintain the resulting
drainage system, for which the corporation was
entitled by law to tax the landowners. Having
invested more in this undertaking and also profited
more than any of the other members of the
corporation, the Russells were still at the head of it
in 1726, but the present duke then was a minor and
the project was in the hands of his uncle and
guardian the duke of Devonshire. For Lord Charles
Cavendish it was also of even more immediate
concern, since as a younger son he deriv ed income
from his mother Lady Rachel Russell's interest in
the Russell estates. 48

The methods used to drain the Bedford
Level in the seventeenth and early eighteenth
centuries had succeeded only in part. Of the
various factors that soon brought back frequent
flooding of the new farmland, the most important
was the lowering of the level as a result of
shrinkage and wastage of the peat surface after
draining. Before long, the water levels in many of
the drainage channels were higher than the land on
either side of them. To add to the problem, the
rivers fell toward the sea so gradually that their
estuaries silted up, further obstructing drainage.
One way of dealing with the flooding was to
shorten the courses of the rivers by constructing
new, steeper "outfalls." This was proposed by the
bill of 1726 with which the Cavendishes were
connected. With the consent of the duke of Bedford
and other landowners, the duke of Devonshire
proposed to finance a new outfall for the Bedford
Level, which had become "choked by the Sands
thrown up by the Tides" and where thousands of

•"Great Britain Parliament, House of Commons Journals (HCJ)
20:600-70. Kntrics from 4 Mar. 1726/27 to 19 Apr. 1726.
41 29 Mar. 1727, HCJ

4i 18, 23 Apr. and 6 May 1729, Ha 21:327, 343, 360.

43 17, 19, 25 Mar. and 3 Apr. 1730, HCJ 21:500, 505, 515, 531.

+•12,21 Mar. 1 729 (1728), HCJ 21:263, 284.

«20, 26, Feb. and 7 Mar. 1 735 ( 1 734), HCJ 22:385, 392. 406.

46 17, 18, 23 Mar. and 7 Apr. 1736, HCJ 72:635, 644-45. 675.

4 '1() May 1726, Ha 20:697.

•'Samuel Wells. The History of the Drainage of the Great Isiel of the
Fens. Called Redford Level: With the Constitution and Lams of the Bedford
Level Corporation, 2 vols. (London, 1830) 1:424-25, 661-62. 4 Mar.
1726(1725), HCJ 20:599.

Cavendish

acres were again frequently flooded if not, as after
the "great Rains and Floods' of 1725/26, "totally
drowned." However, his surveyors could find no
suitable location for the new drainage canal but
through lands lying outside the Bedford Level
proper, and although the Cavendishes organized
strong support for the bill in the affected areas in
Lincolnshire, Harrington and his committee (which
eventually was the whole House of Commons)
failed to bring their negotiations with opposing
Lincolnshire landowners and local commissioners
of sewers (who feared for their autonomy and
authority) to a successful conclusion before the end
of the parliamentary session. 4 ''

The next year the Haddenham Level, an
area in the southern part of the fens as far inland as
the lands involved in the debates of 1726, tried
another method. Moving water to the sea could
also be done by pumping it up into drainage canals
and into embanked rivers. Windmills had been
tried earlier but had met with opposition. The
Haddenham Level bill called for "Mills, or some
orher Fngine," a plan which was approved. 50 Al-
though he was not on the Haddenham committee,
Cavendish attended the Commons while the bill
was discussed, and he was in fact working on
another committee on a similar problem; namely, to
make navigable again a river whose channels had
been destroyed by the tide. 51

When the next petition for a drainage bill
was filed, in 1729, this time by landowners of the
Waterbeach Level, also in the southern part of the
fens, Cavendish was elected (or had himself
elected) to the committee to consider it, 5 - even
though he had no family connection or known
personal interesr, such as property in the area.
Waterbeach Level is in Cambridgeshire. The
petition w as brought by the Member of Parliament
for the county Thomas Bacon, a lawyer and
wealthy landowner, unlike Cavendish a tory, but
like Cavendish a Fellow of the Royal Society with
a great interest in books and a valuable collection. 55
He apparenrly could depend on Cavendish's
interest in the technical problem, returning the
favor seven years later, when he served on the
committee that saw through the Commons
Cavendish's private bill for the sale of his country
estates in Hertfordshire. 54 As to the Waterbeach
drainage petition, the Commons ordered a bill but
never acted on it. Truly effective draining of the

fens had to await the steam engine and an
administrative reorganization into small local units.

The obligation to attend to estate matters of
family and other associates on House committees
remained with Cavendish throughout his sixteen
years in the Commons; in all he was on thirty-five
such committees. Landed property, under British
law, could not be sold or "alienated" from the
designated line of descent without specific
authorization by parliament. Since bills of this type
originared in the House of Lords, they usually
needed only to be confirmed, or at most amended,
by the Commons and took up little time.

Lord Charles Cavendish's official constituencies,
Westminster from 1727 until 1734, and Derbyshire
from 1734 until 1741, involved him in many fewer
committees, even though, when he did work on a
bill for rhem, he and his fellow Member of
Parliament (every constituency except for London
was represented by two members) were in charge
of it, had to chair the committees considering the
petitions and the bills, report on their findings to
the House, draw up the bill, and finally see to it
that it was passed. The regular problems of
Westminster were the usual ones for cities:
repairing streets in "ruinous Condition," clearing
them of the "Filth and Dirt" that covered them,
and keeping them safe at night. 55 In 1729, for
example. Cavendish and his colleagues worked out
a bill designed to correct the ill effects of having
several different privately owned "waterworks" lay
water lines and cover them with pavement that was
neither level nor strong and lasting enough. 5 '' A few
weeks later he and his fellow Member of
Parliament William Clayton were ordered "to bring
in a Bill for appointing a better nightly Watch, and
regulating the Beadles . . . and for better
enlightening the Streets, and publick Passages. . . ." 57

■"Wells, Hedforri Level, 1:426. 744-45 H. C. Darby. "The
Draining of the Kens, A.D. 1600-1800," in An Historical Geography of
England Before A.D. 1800, ed. II. O. Darby (Cambridge: Cambridge
University Press, 1936), 444-64, on 456-59. 4 Mar. 1726 (1725), HCJ
20:599.

*Wells. Bedford Ijvel 1:437-39.

si 14, 23 Feb. 1727 (1726), HCJ 20:740, 769.

'M9, 28 Feb. 1729(1728), HCJ 21:229, 244.

"Sedgwick, //War 2:411.

"23 Mar. 1736 (1735), HCJ 22:645.

"4 Feb. 1729 (1728), HCJ 21:208.

5*19 Feb. 1729(1728), HCJ 21:229.

"10 Apr. 1729, HCJ 21:313.

material

Politics

He worked on such problems for Westminster
again in 1736 and 1737, after he had switched to
Derbyshire. 58 In 1736 he had been appointed to
the commission for the new bridge to be built at
Westminster. The commission had authority to
acquire and condemn the real property needed to
provide for broad carriage approaches — in fact, for
wide streets and regularly aligned new houses —
which eventually transformed the old tangle of
dark alleys that made up Westminster in that area.
But the initial result of their control was a
worsening of the conditions there as property
owners moved away, leaving undone what little
they had contributed toward maintaining the
streets, and as squatters moved in. But even aside
from such special circumstances, Westminster was
at times difficult to represent because it was the
seat of parliament and because it was contiguous
with London and large (its electorate was larger
than London's), the two together containing the
biggest concentration of population in all of
England. Popular dissatisfaction with local or
national matters there often took on tangible forms.
The streets bills in 1729, for example, brought out
thousands of angry people, whose complaints the
Commons refused to hear. London during these
years was in vehement opposition to much of
Walpole's administrative program. In 1733, Walpole's
handling of the proposed excise on tobacco brought
not only local opponents but also the London mob
to Westminster: members of the Commons com-
plained of a "tumultuous Crowd" who "menaced,
insulted, and assaulted" them as they left the
House. By order of the Commons, Cavendish and
Clayton had to notify the high bailiff of Westminster
that such actions constituted a crime and an
infringement of the privileges of the Commons. 59

Like his Westminster predecessors for years,
Lord Charles Cavendish had been elected with
government support, that is, with whig support.
Derbyshire, on the other hand, had been in the
hands of the torics for just as long; Cavendish was
the first whig to be elected for the county since his
father had lost the seat over thirty years before, and
his election was close. 60 His fellow Member of
Parliament there was in fact still a tory, Nathaniel
Curzon, a lawyer and land- and mine-owner who
voted consistently against the administration. 61
Other counties in the area such as Lancashire,
Cheshire, and Yorkshire were also represented by

tories, even ardent Jacobites. As a result.
Cavendish was often not nominated to committees
dealing with matters of concern to Derbyshire,
although, as its representative, he could not be
excluded from such committees, since the speaker
of the house had the obligation to add to a
committee any member who had a legitimate
interest in the matter in question. 62 As a result.
Cavendish was very actively engaged in only a few
private acts initiated by his constituency in
Derbyshire, altogether drawing up only four bills
for them. But he worked on a number of private
acts that benefited Derbyshire even if they did not
deal with the county directly.

The subject of these private acts was road
repair. From the beginning of the century, the
administration and maintenance of English roads
had been undergoing an important change: as the
uses of the roads were converted from mainly local,
foot and animal, traffic to through traffic for
carriages and wagons, the roads were gradually
changed into turnpikes to make the principal users
contribute to their maintenance. At the initiative of
the local parishes responsible for road maintenance
and other interested parties, parliament passed pr-
ivate acts establishing trusts that were given the
responsibility of setting up, financing, and main-
taining the new turnpikes. The earliest turnpikes
had been along the main roads leading to London.
By the 1730s two of these, the so-called Great
North Road and the road from London to Man-
chester, both of which were important links
between Derbyshire and the metropolis, had
already been turnpiked over considerable distances
immediately north of London and immediately
south of Yorkshire and of Manchester. In some
areas, the original turnpike trusts were already up
for renewal. For Derbyshire coal trade, industry,

w 16, 25 Mar. 1736 (1735) and 14. 21 Feb. 1737 (1736), HCJ
22:633. 652, and 22:746, 756.

5 *'12, 13 Apr. 1733. HCJ 11: 11 5-1 6. Plumb, Wa/po/e 2:262-71.

'"Sedgwick, House 1:223. In his first run for a scat from
Derbyshire. Cavendish's vote was 2081, the runner-up tory Curzon's
2044, and the third candidate, the loser, Harper's 1795. Places where
the Cavendishes owned property such as Normanton gave almost all
their votes to Cavendish. Other places such as Thornhill and I'ilslcv
(just outside Chatsworth. it is interesting to note) gave him virtually
no votes. A Copy of a Poll Taken forth* County of Derl/y, The 1 6th, 17th,
ISth, and 20th Days of May, 1 7.1-1 before George Mower, Esq. ; High-Sheriff
for the Said County (Derby, n.d.).

6l Sedgwick, House 1:599.

'■- Thomas, House of Commons, 58.

Cavendish

and agriculture, it was of great importance to
complete the turnpiking of these roads and the
east-west roads lying between them as well. 63

The first such committee that Cavendish
had himself assigned to, in 1735, was formed to
examine the turnpike acts dealing with the part of
the London-Manchester road closest to London/" 4
Three years later he and Curzon drew up the act
that was to close the longest stretch of the London-
Manchester road yet to be turnpiked, thirty-nine
miles of it between Loughborough and Harrington
in Leicestershire and Derbyshire, respectively/' 5
Altogether he worked on twelve private acts for
turnpikes either on or near these two important
highways. In addition he worked on five turnpike
bills for roads west and southwest of London/'' 1 To
no other subject did he devote as much work, and
his interest in this area is strongly confirmed by his
committee work on repairing bridges, and, above
all, by the decade of work he devoted to the
building of Westminster Bridge.

The one local legislative matter Cavendish
took charge of for Derbyshire was typical of these
road bills. In February 1739, he brought a petition
to the Commons from the inhabitants of several
parishes in Derbyshire and Nottinghamshire,
particularly in the area of Bakewell (the town closest
to Chatsworth, the country 7 house of the dukes of
Devonshire), requesting the repair of some of the
major roads linking their towns. Cavendish was put
at the head of a committee of forty-five plus. Five
days later he reported the committee's findings and
the testimony of his two witnesses. The roads in
question had become so deep that they were all
but impassable to carriages and coaches, especially
in the winter. Neither the repair work required by
local statute nor any taxes raised locally for the
purpose were enough any longer to maintain the
roads. The Commons ordered that Cavendish and
Curzon and the two members for Nottinghamshire
draw up a bill, which Cavendish presented in the
middle of March. By the end of March, people
from a town in Nottinghamshire were petitioning
against the bill, claiming it would be a "burden" to
them, and persons connected with a "Company of
Cutlers" in a town in Yorkshire protested that the
bill's provisions for a tollgate near the north-south
route would increase the price of goods for people
in the north. After another forty-five members had
been added to Cavendish's committee early in

April, the opposing petitioners were heard, and
when Cavendish reported the outcome of that
action in the middle of April, the whole House
amended the bill to prevent the undesirable
turnpike. The bill was passed by the House in
early May and became law in June/' 7

The interest of the Commons in turnpike
construction and repair was organizational. Turn-
pike acts made no technical provisions but instead
named the administrative body, the trust, that was
to bear the financial and the — as yet rather
undeveloped — technical responsibility. The turn-
pikes rationalized and improved the network of
English roads, particularly those parts of it centered
on London (and later on the growing industrial
centers such as Manchester) without removing the
roads from control of the local landowners in rural
areas such as Derbyshire and Nottinghamshire,
where Cavendish had most of his landed property/'*

Only rarely did legislation dealing with
mining or manufacturing draw Cavendish's
interest. There was an instance in 1738, when
British ironmongers asked the Commons for a bill
that would protect their market in the American
colonies against competition from the colonies'
own manufactures of iron wares/' 1 ' The decline in
the ironmongers' trade, they argued, threatened
not only the livelihood of a "multitude of Poor"
but the woodlands, whose timber was needed for
the royal navy, the leather manufacturers using
bark, and the balance of trade. During the same
session Cavendish heard the case of button
manufacturers asking for enforcement of a law
against buttons made from woven materials. 7 " The
law was meant to protect the cottage industry of
buttons and buttonholes made with silk and wool
thread using a needle. This industry employed the
"poor" in large numbers, nearly 30,000, and it
protected native textiles such as wool, encouraging,
as the report put it, the consumption of raw silk

'■'Sidney and Beatrice Webb, English Local Government: The Stun
of the King's Highway (London: Longmans, Green and do, 1920), 70.
William Albert. The Turnpike Runil System in England 1663-1840
(Cambridge: Cambridge University Press. 1972), 31—43.

M 18 Apr. 1735, HCJ 22:469.

• '59, 20 Mar. 1 738 ( 1 737), HCJ 23:73, 107.

''''Information from HC.J.

"21 Fcb.-14 June 1739, HCJ 23:242-380.

'"Albert. Turnpike. 22-2-4.

' "1 Feb.-21 Mar. 1738 (1737), HCJ 23:15, 109.

7 "9. 14 Mar. and 10, 18 Apr. 1738, HCJ 23:73, 88 and 142, 156.

Copy rig hi eo

Politics

and wool yarn. The industry was now "much
decayed." Fabric-covered buttons were the reason,
because one person with a loom could do the work
of eight to ten needle workers.

For the entire sixteen years Cavendish
served in parliament, Walpole was prime minister.
Cavendish stepped down in 1741, Walpole in 1742.
In addition to whatever family loyalty Cavendish
may have felt toward Walpole, he would have been
drawn to him for his similarity of outlook. Walpole
preferred the "mathematical, provable side of
administration." Since the Revolution, political
arithmetic had been energetically implemented by
the administrators, who were often Fellows of the
Royal Society who believed that similar methods
applied to government and nature. English
government, Walpole's biographer says, was
"revolutionized" by these professional public
servants. 7 ' Their quantitative approach agreed well
with Walpole's penchant for exacting detail.

Cavendish did not always vote with
Walpole, however. In 1725, the year Cavendish
entered parliament, William Pultney broke with
Walpole, 73 and there is at least the suggestion that
Cavendish sympathized with Pultney 's opposition
whigs. In any event, Cavendish had other important
interests to serve, his family's of course but also
London's and Westminster's. He continued to serve
Westminster even after he stopped representing it
in parliament, as we will see. His interests would
seem to have been closer to the commercial and
financial ones of the city than to those of the
country (he sold his own country home in 1736)
and the colonies. The episode of Walpole's excise
tax on tobacco in 1733 brings this out. Walpole
almost fell from power because of it, and
Cavendish did nothing to help him. Walpole's
excise tax on tobacco was in the interest of Virginia
growers, who had long resented the dominion over
their business of the London tobacco brokers.
There was violent opposition to this tax in the city,
which nearly prevailed. When Walpole got his bill
passed, by a narrow vote, the city raised a petition
against it. Walpole's majority melted away, but he
did manage to get the Commons to refuse to hear
the petition. Walpole survived, but barely, and not
without a riot outside the Commons. Cavendish
supported the bill in the beginning, then he voted
with the opposition on the city's petition against it.
The king, who was strongly with Walpole on this

bill and regarded opposition to it as treason, called
Cavendish "half mad" and Lord James Cavendish,
who voted exactly as Charles did, a "fool." 73

Cavendish's political career as a Member of
Parliament ended in 1741, not by defeat but by
choice. If he sensed it or not, he left politics at about
the time his family could dispense with his services.
To the mid 174()s but not beyond, the outcome of the
Clorious Revolution remained in question; for up to
then the tories were predominantly a Jacobite party
ready to ally itself with France to restore the Stuart
dynasty. Thereafter, the vigilance of the Devonshire's
could be relaxed. Lord Charles Cavendish could,
with clear conscience, consider another path in life.

Cavendish was elected to the Royal Society about
two years after he was elected to the Commons. In
1 736 he served on the council of the Royal Society
for the first time, though not again until the year
after he left parliament, thereafter serving on the
council almost without interruption for twenty-five
years. His work on the council and on the
committees of the Royal Society would take the
place of his complementary work in parliament.

In the course of his sixteen years in the
Commons, Cavendish associated with about two
hundred Members of Parliament on parliamentary
committees. Very few of them were Fellows of the
Royal Society, at most a dozen, with maybe another
half dozen becoming Fellows after he had left the
Commons, and none of them were to become close
scientific associates of his. 74 Of candidates for
membership in the Royal Society, Cavendish
signed the certificates of only two men with whom
he had served on committees in parliament: a

"Plumb, Walpole 2:234.
"Plumb, Wa/pole Z:\ZZ-24, 127.

"Plumb, Walpole 2:250-71. Thomas. House of Commons, 68-71.
John. Lord Hervey, Memoirs of the Reign of George the Second from His
Accession to the Death of Queen Caroline, ed. J. W. Croker, vol. 1
(London, 1884), 200. Sedgwick, The Home 1:537.

"Members of the I louse of Commons associated with Lord Charles
Cavendish w ho were also Fellows of the Royal Society: Thomas Sclater
Bacon, F.R.S. 1722: Benjamin Bathurst. F.R.S. 1731; Charles Calvert, Lord
Baltimore, F.R.S. 1731; Thomas Carrwright, F.R.S. 1716; I^ord James
Cavendish, F.R.S. 1719; John Conduitt, F.R.S. 1718; James Dawkins.
F.R.S. 1755; Thomas, Lord Gage, F.R.S. 1728; Fdward Hooper. F.R.S.
1759; Robert Hucks, F.R.S. 1722 (or possibly his father, William); Sir
James Lowther, F.R.S. 1736; Henry Pelham, F.R.S. 1746; Hugh Hume
Campbell. Lord Polwarth (until 1740, then earl of Marchmont), T'.R.S.
1753; Sir Hugh Smithson (after 1750 carl of Northumberland, after 1766
duke of Northumberland) F.R.S. 1736; Charles Stanhope. F.R.S. 1726; Sir
John Brownlow, Lor] Tyrconnel, F.R.S. 1735; Thomas Walker/?/. T'.R.S.
1730; and Kdward Wortlcy Montagu, F.R.S. 1750.

Cavendish

distant relative, Sir James Lowther of Whitehaven,
who had communicated experiments to the Royal
Society, and Edward Hooper. 75

Gentleman of the Bedchamber

The duke of Kent was gentleman of the
bedchamber to George I, and in 1728 his future
son-in-law Lord Charles Cavendish was appointed
to the same position, only to the prince of Wales,
Frederick. Cavendish was indeed a "gentleman,"
though as son of the duke of Devonshire he was
referred to as "lord" of the bedchamber to the
prince. 7 '' With this position Cavendish was now a
man both of parliament and of the court-in-waiting.
He was a consort to the man who stood next in line
for the throne, required to be in attendance for
much of the day when it came his turn. The
appointment presumably was made by the king
but not against the wishes of the prince. In any
case, the relations between Cavendish and the
prince were good; Cavendish's second son would
be named Frederick after the prince, who would
stand in as his godfather.

As it turned out, this prince did not live
long enough to become king but long enough to be
a political force in his own right and the occasion of
the scandal of the reign. Frederick was born in
Hanover in 1707 and remained there until
December 1728, when he was brought suddenly to
Fngland because word was received at court that
he was about to marry the princess royal of Prussia.
The marriage had been negotiated and sanctioned
by George I, but in 1727 his father came to the
throne, and George II did not see eye to eye with
the king of Prussia and called off the marriage. In
submitting, the prince detested his father for
keeping him dependent. He later married Princess
Augusta, daughter of Frederick, duke of Saxe-
Gothe, with his father's approval, but the prince
turned this marriage into a weapon against his
father. Competing with his father for popularity in
the country, the prince formed an opposition court,
welcoming into his household ambitious young
men like Pitt, Lyttleton, and the Grcnvilles, and he
developed an intense dislike for Robert Walpole,
his father's favorite minister. Fond of music and
literature, he sought the company of men of wit
and learning, such as ( Chesterfield, (Carteret,
Pukeney, Cobham, and Wyndham. He associated
with persons who had an interest in science too, for

which there was a precedent in the family. When
Frederick's father had been prince of Wales, his
secretary was the astronomer Samuel Molyneux,
who was a close friend and colleague of James
Bradley; he had his own instrument-maker as well.
Later, as George II, his master of mechanics was
the very competent Robert Smith, professor of
astronomy and natural philosophy at Cambridge. 77
John Theophilus Desagulicrs, demonstrator of
experiments in the Royal Society, was chaplain to
Frederick, prince of Wales, to whom Desagulicrs
dedicated his Course of Experimental Philosophy. 1 * So
was Thomas Rutherforth, Fellow of the Royal
Society and professor of divinity at Cambridge,
where he lectured and w rote on natural philosophy 7 ''
The princess's chaplain, Caspar Wetstein, was a
correspondent of the great mathematical scientist
Filler. x " In 1731, we know, the prince was pleased to
be seen in the company of men of science, for he
attended a meeting of the Royal Society at which
experiments on electricity, magnetism, phlogiston.

"Sir James Lowther was elected in 1736 on the strength of a
proposal in which Cavendish's signature was only preceded by that
of the president of the Royal Society: we discuss this relative and
wealthy land and mine owner in another place On the proposal in
1759 of Kdward Hooper, Cavendish's signature was less prominent,
sev enth out of twelve. Hooper was introduced to the Society as "one
of the commissioners of his Majesties customs, a gentleman of great
merit, & well versed in various branches of usefull learning." Royal
Society Certificates, vol. 1. no. 5. f. 118 (Lowther), and vol. 2, no. 1(1.
f. 177 (Hooper). Cavendish had first joined a committee with
I looper. a lawyer and opposition whig, over twenty years before his
election to the Royal Society. Hooper had been on Cavendish's
committee for the turnpiking of the Derbyshire roads around
Bakewell, and in turn Cavendish had sat on Hooper's committee for
naturalizing Andrew (then Adrian) Coltec Ducarel. D.C.L. and later
F.R.S. Sedgwick. House 2.147.

"'■John Kdward Smith and W. Parkinson Smith, The
Parliamentary Representation of Westminster from the Thirteenth Century to
the Present Day, vol. 2 (London: Wightman, 1923), 272. James
Douglas, carl of Morton, w ho became president of the Royal Society
while Cavendish was a member, had held a parallel position at court,
as lord of the bedchamber. "Douglas, James. Fourteenth Karl of
Morton," DNB 5:1236-37, on 1236.

"Frederick Louis, Prince of Wales." DNB 7:675-7X. I-:. G. R.
Taylor. Mathematical Practitioners of Hanoverian England, 1714- IH40
(Cambridge: Cambridge University Press, 1966), 10, 135-36.

7 "J. T. Desagulicrs, A Course of Experimental Philosophy, vol. 2
(London, 1744). Like many subscription books, this one was long in
the making; among its subscribers were Newton, Ceorge I, George
II, and Queen Caroline, all but George II then dead.

"Thomas Rutherforth later became chaplain to the princess
dowager as well. "Rutherforth. Thomas," DNB 17:499-500. In 174*
he published his lectures at Cambridge as .4 System of Natural
Philosophy, a well-known text which we discuss when we take up
scientific teaching at Cambridge.

80 "Extract of a Letter from Professor Euler, of Berlin, to the Rev.
Mr. Caspar Wetstein. Chaplain to Her Royal Highness the Princess
Dow ager of Wales," PT 47 ( 1 751 ): 263-64.

CopynqlilM

Politics

and phosphorous were performed. 81 He was thought
to have a eertain special interest in astronomy. Filial
competition, we suspect, if not native interest,
would have drawn Frederick, prince of Wales, to
the scientifically knowledgeable Lord Charles
Cavendish. (Fredericks son, George III, would be
the first British monarch to be tutored in science. 82 )
There may also have been a political
sympathy between Charles and Frederick, but in
personality this studious gentleman of the bed-
chamber would seem to have had little in common
with this rakehell-living prince. Confronted with
the prince's passionate rebellion, the king drew the
line in 1738; thereafter no one who paid court to
the prince of Wales or his wife was admitted to the
king's presence at any of the royal palaces.* 0 But by
the year of the prince's banishment, Lord Charles

Cavendish had long before left his service, having
resigned in October 1730. 84

"'Charles Richard Weld, A History of the Royal Society, 1 vols, in 1
(New York: Arno Press, 1975) 1:465-66.

"-George III was tutored by George Lewis Scott, a mathematical
colleague of Charles Cavendish. Leonard Weiss, Watch-Mating in
England, 1760-1820 (London: Robert Hale, 1982), 21-22. This king
had a number of other connections with science: he had an
instrument-maker provide him with a set of demonstration
apparatus; he had a private observatory; Lord Bute, another tutor and
his principal advisor, was a botanist; he provided an income for the
astronomer William Herschel; and he gave large sums to the Royal
Society for its projects.

8, Duke of Grafton to /Theophilus, Earl of Huntington/, 27 Eel).
1738, in Great Britain. Historical Manuscripts Commission, Report on
the Manuscripts of the Late Reginald Roar/en Hastings, Esq.. of the Manor
House, Ash//y /le la louche, 4 vols. (London: His Majesty's Stationary
Office, 1928-47)3:22.

'"Entry on 17 Oct. 1730 in The Historical Register, vol. 15: The
Chronological Diary (London, 1 730), 64.

CHAPTER 2

^cience

De Moivre Circle

Families of the landed aristoeraey in Elngland
settled their estates on their eldest sons and turned
out their younger, such as Lord Charles Cavendish,
with the expectation that they would contribute to
their upkeep by entering one of a highly restricted
number of suitable professions. We can say with con-
fidence that Cavendish's options did not include
science, regardless of how great an interest he might
have had in it. He entered politics, as we know.

If not as a profession, how then would
science have appeared to Lord Charles Cavendish?
We should point out here that science did already
show some of the essential characteristics of a
profession, though they had not been brought
together, and they were probably less apparent
(and less interesting) in his time than they are to us
looking back. Scientific instruction was widely
available on a catch-as-catch-can basis, often taking
the form of self-instruction from books or tutoring
or apprenticeship. Lectures on science could be
heard in the universities, certain kinds of schools,
shops of instrument-makers, coffee houses, and
private homes. In the middle of the eighteenth
century, a father educating his son in law, pointed
out that in London, in addition to reading books on
law, his son could attend a "variety of lectures both
of mathematics & experimental philosophy." 1 There
were various circles avid for knowledge of the new
science, and they made possible a variety of
livelihoods, which were often combined, but which
hardly ever paid for scientific research. Practitioners
of science, in addition to teaching, could earn
money by consulting,-' publishing popular books on
science, making and selling scientific instruments,
or serving a wealthy patron. There were only a very
few government scientific jobs such as astronomer
royal. Public recognition in science took the form of
membership in, honors bestowed by, and approval
of work for publication by a mixed group such as
the members of the Royal Society. Such standards

as existed were neither very rigorous nor uniform.
The practitioner of science worked in science for
himself, largely on his own initiative, whether it
earned him a living, a distinction, or simply per-
sonal satisfaction.

If by comparison with the professions,
science in the time of our Cavendishes is found
wanting in certain ways, it is nonetheless true that
the professions themselves were then loosely
organized and regulated, and that they, like
science, were undergoing change. Physicians, for
example, acquired a positional status through
professionalism in the nineteenth century, but in
our eighteenth century "individual and personal
characteristics were of greater consequence"; for
one thing, formal licensing laws did not yet exist.'
By the same token, the clergy was an extraordinary
mix by any standard. Much of it was impoverished,
yet intellectually inclined, and to this portion of the
clergy science owes a large debt. The bishops of
the church, who were well to do, were sometimes
highly qualified men of learning and ability but
often men of rank and ease and little else to
recommend them. 4 In law, the inns of court had
abandoned their original function of teaching stu-
dents, and Oxford took little interest in them, which
left them to study on their own and attend courts at
Westminster or work in an attorney's office. Adminis-
tration was another mix of the able and the indif-
ferent; English government, apart from the central
government in London, consisted of practically
autonomous local units, which did not form a sys-
tem but a "hotch-potch of authorities and con-

'Sollom Kmlvn to John Ward. 8 Jan. 1758. "Letters of Learned
Men to Professor Ward. BL Add Mss 6210.

^Larry Stewart, "Public Lectures and Private Patronage in
Newtonian Kngland," /sis 11 (1986): 47-58, on 55-56.

>W. E Bynum, "Health, Disease and Medical Care," in '/'he
Ferment of Knowledge: Studies in the Historiography of Eighteenth Century
Seienee, ed. G. S. Rousseau and R. Porter (Cambridge: Cambridge
University Press, 1980), 221-53, on 234.

J L. B. Namicr, Crossroads of 1 'over: Essays on Eighteenth-Century
England (London: H. Hamilton, 1962), 185-86.

Cavendish

flicting institutions," whose officials were not profes-
sional bureaucrats but were, at least nominally,
unpaid and were drawn from a "half-educated"
class. 5 Science, to Lord Charles Cavendish, would
have seemed like a disorganized enterprise, but
then so would have the activities of the lawyer and
doctor, the surgeon and apothecary, the merchant
and manufacturer, many of whom began with little
formal schooling, underwent apprenticeship, and
then set up practice where they found clients,
largely unhampered by restrictions.

It was, of course, unthinkable for Lord
Charles Cavendish to enter any of the learned
professions or administration or business — or
science, even if it had been regarded in the same
light as the learned professions. If his social
circumstances had been radically different, given
his talents and inclinations, we suspect that he
would have been happy as an instrument-maker,
associating with men of science, and earning three
or four pounds a week. What he did do was to
pursue science on the side, the only course open to
him, and on his own initiative, in one way or
another, he got a good foundation in science.

In his twenties, Lord Charles Cavendish enjoyed
several years of relative freedom from the duties of
family and public office. Circumstantial evidence
leads us to think that during these years he
continued his education in London. His teacher, or
one of his teachers, may have been the great
mathematician Abraham De Moivre.

Fifty years De Moivre's junior, Matthew
Maty was his close friend and the author of a
valuable biographical piece on him. To Maty we
owe a list of De Moivre's eminent mathematical
friends: Newton, Kdmond Halley, James Stirling,
Nicholas Saunderson, Martin Koikes, and, on the
Continent, Johann I Bernoulli and Pierre Varignon.
(To this list of mathematical friends we add from
other sources William Jones h and Brook Taylor, 7
and there were still others.) Maty also named De
Moivre's pupils or, to use the exact French word,
disciples: Lord Macclesfield, Charles Stanhope,
Ccorge Lewis Scott, Peter Davall, James Dodson,
and Cavendish.* (John Colson should be included
among his pupils, and no doubt others. 9 )

Since Maty gave only last names, we are
forced to speculate about whom he meant by
"Cavendish." Writing in the late 1750s, Maty

would unlikely have meant Henry Cavendish, who
had only recently come down from Cambridge and
was not yet a Fellow of the Royal Society. Nor, we
think, is it likely that he would have had in mind
William Cavendish, duke of Devonshire; for the
judgment Maty wished his readers to make of De
Moivre was of his standing among accomplished
mathematicians and not within society at large, and
so far as we know, none of the early dukes of
Devonshire had a mathematical reputation, though it
is conceivable the first duke, a man of many reputa-
tions, had something of one. The likeliest possibili-
ties narrow down to two, Lord Charles Cavendish
and his uncle Lord James Cavendish. 10 Both were
active in the Royal Society, and both were proposed
for membership in the Society by the good friend of
De Moivre, the eminent mathematician William
Jones. Both subscribed to De Moivre's Miscellanea
analytica de seriebus et quadraturis, which was pub-
lished in 1730, and which was the first mathematical
or scientific book to which Lord Charles sub-
scribed. The duke of Devonshire was also a
subscriber to this book, and it is just conceivable
that Lord Charles and Lord James were both
pupils of De Moivre and that various Devonshires
were as well. (De Moivre called at the Devonshire
house in London, very possibly in the capacity of
mathematical tutor; see below.) Because of the
reasonable possibility that by "Cavendish," Maty
meant Lord Charles Cavendish, and, in any event,
because of the evidence it provides of the mathe-
matical culture of the close-knit Cavendish family, we
include the following brief discussion of De Moive.

"Basil Williams, The Whig Supremacy, 1714-1760, 2d rev. cd. by C.
II. Stuart (Oxford: Clarendon Press, 1962), 44-45. 62-63.

''De Moivre tailed William Jones his "intimate friend" in the
prefaee to his book The Dor trine of Chances; or, a Method of Calculating
the Probability of Events in Play (London, 1718), x.

7 l)e Moivre called Brook Taylor his "worthy Friend" in his
Doctrine of Chances, 101. He had a correspondence with Brook Taylor,
described in Ivo Schneider, "Der Mathcmatiker Abraham de Moivre
(1667-1754)," Archive for History of Exact Sciences 5 (1968): 177-317,
on 196-97.

"Matthew Maty. Mcmoire sur In vie et sur les escrits de Mr. Abraham
de Moivre ( The Hague, 1760), 38-39.

'In the foreword to his first book, Animadversiones, I)c Moivre
referred to John Colson as one of his pupils, noted by Schneider,
"Abraham de Moivre," 189.

'"Lord James Cavendish was proposed for membership in the
Royal Society by William Jones on 19 Mar. 1718/19, and was
admitted on 16 Apr. 1719. Royal Society. JB 11: 311 and 326. The
other Lord James Cavendish, Lord Charles's brother, is not a likely a
candidate for Mary 's "Cavendish."

Science

The friends and pupils of De Moivre
spanned two generations: De Moivre was Newton's
junior by twenty-five years and Cavendish's senior
by about the same number of years. Many of them
were prominent in the Royal Society: Newton,
Koikes, and Macclesfield were presidents, Cavendish,
Jones, Davall, Scott, and Stanhope members of the
council, Halley a paid corresponding secretary and
also editor of the Philosophical Transactions, and
Taylor, like Maty himself, a secretary. De Moivre 's
pupils, in part through De Moivre, had a living
connection with the great scientists of the recent
past. To judge by their work, De Moivre encouraged
in them a wide-ranging response to the problems
of quantity, both scientific and practical, of the
early eighteenth century. There was a social con-
nection too: Cavendish, for example, met privately
as well as publicly with Koikes, Macclesfield, Jones,
Davall, and Stanhope. There is reason to believe
that De Moivre fostered a sense of connection
between his pupils, as he evidently brought them
together at social evenings and later kept them
"together as a kind of clique." Maty, De Moivre 's
friend and biographer, contributed by noting every
work published by De Moivre 's pupils in his Journal
Britannique. xx They appear together in other connec-
tions as well. 12 If we leave aside the foreigners
named by Maty, we are directed by him to a select
few within the larger group of British mathemati-
cians in the early eighteenth century with whom
Cavendish came to be closely connected. Kor conveni-
ence, we will speak of a "De Moive circle," whose
members will give us an idea of the mathematical
world in which Lord Charles Cavendish may have
completed his (other than self-) education.

De Moivre is not an Knglish name, and Maty wrote
about him in Krench; we now explain. The learned
world of London was greatly enriched by Protestant
refugees, Huguenots, forced to leave Prance after
the revocation of the edict of Nantes. Within the
Cavendish family, as we have seen, the Huguenot
Ruvignys settled in Greenwich (a prophetic location)
and encouraged other refugees to follow their
example. 15 De Moivre 's father was one of a large
number of Huguenot surgeons and physicians to seek
asylum, in 1686, in Kngland, where he and his son
were naturalized. 14 De Moivre was then nineteen
and a student of mathematics.

In De Moivre 's mind, his arrival in Kngland

became so closely identified with his discovery of
Newton's work that although two or three years
elapsed between the two events, to him they
seemed simultaneous. Kor biographers of Charles
and Henry Cavendish, it is gratifying that the
meeting between De Moivre and Newton's work
occurred in the house of the earl of Devonshire. It
was probably in 1689, when Newton spent a good
deal of time in London as a member for Cambridge
of the Convention Parliament, and when Devonshire
enjoyed the fruits of the revolution as a prominent
member of parliament and of the court of William
and Mary. De Moivre first saw Newton as Newton
was leaving Devonshire's house after presenting a
copy of his Principia. Shown into the antechamber
where Newton had just left his book, De Moivre
picked it up expecting to read it without difficulty.
He found that he understood nothing at all. Whether
it was on that first encounter or later, when he
studied his own copy of the work, he felt that all of
his mathematical studies so far, which he had
considered entirely up to date, had really taken
him only to the threshold of a new direction. 15 De
Moivre 's confidence in his own gifts proved to be
well founded, however, for he promptly mastered

"Uta Jansscns, Alatthieu Alaty and the Journal Britannique,
1750-1755 (Amsterdam: Holland University Press, 1975), 17.
Augustus De Morgan, "Dr. Johnson and Dr. Maty," .Votes and Queries
4(18571:341.

l2 Thcy appeared together, for example, with a much larger
number of like-minded persons in the following context. De Moivre
republished his mathematical papers from the Philosophical Trans-
actions in a book, mentioned above. Miscellanea anahtica de seriebus el
quadratures ( London, 1 730). As was customary with technical books, it
was sold by subscription and listed the names of the subscribers; this
list could serve as a guide to British mathematics and its patrons in
the early eighteenth century. The Cavendishes, as noted, are sub-
scribers, and the book is dedicated to Koikes. With an exception or two,
the friends and pupils of De Moivre, as given by Maty, are all there.

"Mary Berry, Some Account of the Life of Rachael Wriothesley Ijidy
Russell. . . Followed by a Series of Letters . . . (London. 1819), 73.

l4 Fathcr and son, "Abraham and Daniel de Moivre," are listed
as being in Kngland as of 16 Dec. 1687, in a request to the Attorney
or Sollicicor Gcnerall to prepare a bill for royal signature making
them free denizens of the kingdom. Lists of Foreign Protestants, and
Aliens, Resident in F.ngland 16IH-16SH, ed. W. Durrant Cooper
(London, 1862), 50. Samuel Smiles. The Huguenots: 'Their Settlements.
Churches, and Industries in F.ngland and Ireland (New York, 1868),
235-38.

l5 Mary, Mimoire. 6-7. Although the Principia was published in
the summer of 1687, there is no evidence that Newton came to
London to distribute copies of it at that time. Moreover, it would
have been of no advantage to either Newton or De Moivre that
summer to seek the earl of Devonshire's patronage, since he was
then so much out of favor at court; in 1688 the carl took refuge at
Chatsworth to avoid being arrested by the king. By 1689, however,
James II had been displaced by William and Mary, at whose court
Devonshire had a great deal of influence.

the new mathematics, with the result that Newton
is said to have referred persons asking him about
his work to De Moivre, who knew it better than he-
did. ,(> Through the astronomer Edmond Halley, De
Moivre was introduced to Newton properly and as
well to the scientific society of London, which led
to his election to the Royal Society. He made him-
self av ailable to Newton in a variety of capacities:
he sent news and results of Newton's work to
colleagues abroad; 17 he translated and took charge
of Newton's publications;' 8 he defended Newton; 19
and he kept philosophical company with Newton
at the Rainbow coffee-house and elsewhere.- 0 De
Moivre 's own work drew heavily on Newton's,
which he acknowledged by dedicating his
masterwork, a treatise on probability, Doctrine of
Chances, to Newton. This friend of Newton, Halley,
and other prominent Fellows of the Royal Society
and correspondent of leading mathematicians on
the Continent was, we speculate, Lord Charles
( lavendish's teacher in advanced mathematics.

De Moivre just might have been
Cavendish's teacher in natural philosophy too. He
gave lectures on the subject but without much
success, since his English was not good and neither
were his skills as an experimental demonstrator. 2 ' It
was otherwise with his teaching of mathematics,
which has its own language, though this is not to say
that he made a good liv ing at it. He barely subsisted.
In just what setting he taught mathematics, we are
uncertain. We know only that he tried most of the
ways that a person could make money through
mathematics short of writing popular manuals. In
16H9 a committee in the Commons considered how
to raise funds to establish a royal military "Academy"
in or near London or Westminster and to aid
"French and Irish Protestants, who are fled from
France and Ireland for their Religion."- The
project apparently did not die, for three years later
we find another reference to a "Royal Academy,"
this time linking it to De Moivre. Richard Sault,
who published a mathematical proof in the
Philosophical Transactions, and De Moivre were to
be its mathematics teachers. Later on Sault ran a
so-called mathematical boarding school, calling
himself a "professor of mathematics," 23 and De
Moivre may have taught at this or at similar
schools. Twice he presented himself as a candidate
for the Lucasian professorship of mathematics at
Cambridge. Well connected in mathematical circles

Cavendish

and highly regarded for his work, he still could not
get a good job. Even his conversion to the Church
of England in 1705 could not alter the fact that he
was an alien. Toward the end of his (long) life, he
worked out of Slaughter's Coffee House in St.
Martin's Lane, solving problems of games and lives
for a fee and, perhaps, for a handout. 24

De Moivre had a philosophical viewpoint,
which he believed was close to Newton's. 2,5
Probability is useful for gamblers, De Moivre wrote
in Doctrine of Chances. It is for fun and gain, but it is
also for the reasoning mind: it clarifies the world
through the paradoxes it exposes, since chance is
the denial of luck, of which there is no such thing
in "nature." The doctrine of chance, De Moivre
said, supports the doctrine of design: probability
can grow until it becomes demonstration, and so
the order and constancy of nature express design. 2 ''
And so from whist to Cod, mathematics applies
and illuminates, and bright young men like Lord
Charles Cavendish were caught up in its charms, as
revealed by De Moivre.

In the seventeenth and eighteenth centuries,
mathematical tutoring was a common finishing
school for "gentlemen." It provided a useful skill

" Ian 1 lacking "Moivre, Abraham dc." DSB 4:452-55, on 452.

'"For example, concerning copies of Newton's I'rimipia
promised by De Moivre: letters from Pierre Yarignon to Newton, 24
Nov. 1715. and from Johann Bernoulli to Leibniz, 25 Nov. 1713; in
The Correspondence of Isaac Newton, vol. 6: 11 13-17 IN, ed. A. R. Hall
and L. Tilling (Cambridge: Cambridge University Press, 1976),
42-13, 44-45.

'"David Brew ster. Memoirs of the Life ; Writings, ana" Discoveries of
Isaac Newton, 1 vols. (Edinburgh, 1855) 1:248. Schneider, "Abraham
de Moivre," 212-13.

'"'In Newton's dispute with Leibniz over the invention of the
calculus. Hacking, "Moivre," 452.

-"Frederick Charles Green, Eighteenth-Century frame. Six Essays
(New York: I). Appleton, 1931), 31.

-''Schneider. "Abraham de Moivre," 208.

- The funds were to be taised by licensing hackney coaches, the
subject of the bill under consideration. 22 Apr. 16X9. HC'.J 10:97.

-' The project was advertised in the short-lived Athenian Mercury.
E. C». R. Taylor. Mathematical Practitioners of Tudor and Stuart England
(Cambridge: Cambridge University Press, 1954), 289.

M For a long time Slaughter's was De Moivre 's mailing address.
Bryant Lillywhitc, London Coffee Houses. A Reference Hoot of Coffee
Houses of the Seventeenth, Eighteenth, and Nineteenth Centuries (London:
George Allen & Lnwin. 1965), 421-22.

B. Sheynin, "Newton and the Classical Theory of
Probability," Archive for History of Exact Sciences 7 (1970-71): 217-43,
on 230.

-' De Moivre, Doctrine of Chances, iii-vi. Until the nineteenth
century random events were unthinkable: De Moivre is called one of
the "deterministic probabilists" in Lorraine Daston. Classical
Probability in the Enlightenment (Princeton: Princeton I niversity Press,
1988), 10.

Copy rig hi

Srietirt

5.*

for men who sought public office and lacked the
advantage of rank.- 7 It also prepared men who
intended to make a living directly from
mathematics, especially teachers. In becoming a
pupil of De Moivre, Lord Charles Cavendish was
on a path that was uncommon for anyone and
especially for someone whose career and oppor-
tunity were so clearly marked out; for it would lead
him to scientific research and administration.

Of De Moivre's friends, as opposed to
pupils, James Stirling and Brook Taylor were
mathematicians of the first order. Stirling, an Oxford-
educated Scot, taught mathematics privately and
later in a successful school in London, the Little
Tower Street Academy. His first paper, in 1718,
dealt with Newton's differential method, the
subject of his major work, in 1730, Methodus
differentia/is. With Newton's help, he was elected to
the Royal Society in 1726, shortly before
Cavendish's election. Stirling spent the last half of
his life in Scotland surveying, administering
mining enterprises, and teaching mathematics. 28
Brook Taylor came from a well-to-do family with
strong interests in music and art. To these interests
Taylor added mathematics and experimental
natural philosophy, which led to his election to the
Royal Society in 1712. His most important work
was a treatise in 1715 on the method of increments
and its relationship to Newton's fluxions, Methodus
inrrementorum directa and ///versa. With De Moivre,
he joined the Royal Society's defense of Newton's
claims in the priority dispute over the invention of
the calculus. 2 '' Kdmond Halley had very broad
interests and competences including mathematical
ones, but his outstanding work was in astronomy.
He was educated at Oxford, to which he returned
as Savalian professor of geometry; and from 1720
he was astronomer royal. 50 The Lucasian professor
of mathematics Nicholas Saunderson we will
discuss when we take up scientific education at
Cambridge. Of De Moivre's friends, that leaves
only William Jones and Martin Folkes, both of
whom Cavendish came to know very well.

William Jones was another mathematics
teacher under whom Cavendish may well have
studied. 51 Early on, Jones published a book on
navigation and another, a syllabus of mathematics,
which drew the attention of Halley and Newton,
both of whom became his friends. He settled in
London where he taught and then tutored in

mathematics. With one of his pupils Philip Yorkc,
later earl of Hardwicke and lord chancellor, he
became friends and later traveled with him on his
circuit. Another pupil was Ceorge Parker, later earl
of Macclesfield, with whom he had an especially
close and enduring association. F"or years he lived
at Macclesfield's home, Shirburn Castle, where he
served as secretary to Macclesfield's father.
Through this connection he was appointed deputy
teller to the exchequer, a position similar to
Macclesfield's own there. Jones published a
number of original papers in the Philosophical
Transactions, edited important tracts of Newton,
and served with De Moivre on the committee of
the Royal Society on the discovery of the calculus.
He intended to write an introduction to Newtonian
philosophy but died before he completed it. His
library of mathematical books and manuscripts was
reputed to be the largest in the country. Jones was
an important figure in the Royal Society, to which
he was elected in 1712, and he was an important
personal and scientific link between Newton and
the science of his day and Lord Charles Cavendish. 52
Martin Folkes studied at Cambridge under
one of the first Newtonian mathematical teachers
there, Richard Laughton, of Clare College. At the
age of twenty-three, in 1714, he was elected
Fellow of the Royal Society. He published several
papers in the Philosophical Transactions dealing with
astronomy and with the proportions of English
weights and measures to the French and on those
of the Royal Society to those in the exchequer and

27 A. J. Turner. "Mathematical Instruments and the Education of
Gentlemen," Annals of Science 30 (1973): 51- 88, on 51-54.

JK K. (I. R. Taylor, Mathematical Practitioners of Hanoverian
England, 1 714-1 840 (Cambridge: Cambridge University Press, 1966).
144-15. P. J. Wallis, ".Stirling. James." DSB 13: 67-70.

-"Phillip S. Jones, " Taylor, Brook," DSB 13: 265-68. L.
Fcigcnbaum, "Brook Taylor and the Method of Increments," Arrhke
for History of Exact Sciences 34 (1985): 2-140. on 6-7.

"'Colin A. Ronan, "Halley, Kdmond," DSB 6:67-72.

"It was Jones's practice to hand out transcripts of Newton's
mathematical writings to his pupils; that is the likely way Lord
Charles Cavendish came to make a copy of Jones's transcript of
Newton's Arris Analyticae Specimina she Geometria Analjrica.
Cavendish later loaned his copy of the transcript to the
mathematician Samuel Horsley. who was preparing a general edition
of Newton's papers. Isaac Newton, Mathematical Papers of Isaac
Newton, ed. D. T. Whiteside, 8 vols. (Cambridge: Cambridge
University Press, 1%7-81) l:xxiii; 8:xxiv. xxvii.

J 2"Jones, William," DNB 10:1061-62. 'Taylor, Mathematical
Practitioners of Tudor and Stuart England. 293-94. "Jones (William)."
in Charles Hutton, Mathematical and Philosophical Dictionary vol. 1
(London, 1796). 643—14. Thomas Birch to Jemima Grey, 5 Aug. 1749,
BL Add Mss 35397. ff. 198-99.

Cavendish

elsewhere in England. Picked by Newton as his
vice president, Koikes went on to become
president both of the Royal Society and of the
Society of Antiquaries. Thomas Birch wrote in his
memoir of Koikes that he brought to antiquities
the "philosophical spirit, which he had contracted
by the cultivation of the mathematical sciences . . .
These talents appeared eminently upon the
subjects of coins, weights and measures . . ."
Kolkes's Table of English Silver Coins, giv ing the
grains and carats and physical descriptions of all the
coins, reign by reign, was a showpiece of
quantitative work in historical scholarship."

As we have seen, De Moivre counted
among his friends a good many eminent men of
science. By and large, his "pupils," as opposed to
his "friends," did not do work of the same
distinction, but they hold an interest of another
kind. That has to do with the diversity of their
lives in mathematics: some made a living from it,
some made it an avocation, some took jobs that
required a grasp of numbers, and some, like
Cavendish, took quantitative reasoning in direc-
tions of research in fields outside of mathematics.

James Dodson, the youngest of De Moivre 's
pupils, earned a good living through mathematics
as an accountant, a teacher, and a writer of practical
books. At the end of his life, he was master of the
Royal Mathematical School at Christ's Hospital, in
London, a coveted job (decided by interest as
much as by merit; William Jones was passed over
for it); his pupils — "Mathematical! children,"
Newton, one of the governors of this school, called
them — were intended for the navy or trading
companies. M Dodson extended his teaching and
his income through books, dedicating the first
volume of his Mathematical Repository to De Moivre
and the third volume to a fellow pupil, Macclesfield.
The Repository was a collection of questions and
answers for "beginners," which meant that it was
concerned with those problems of quantity that could
be solved without the need of fluxions. The ques-
tions, some five hundred in all, reflect the practical
concerns of the time, the unknowns in the alge-
braic expression of the questions standing for miles
traveled, yards of cloth, wages, charitable contribu-
tions, gallons of beer, sizes of regiments, quantities
of wheat, anhnuities computed by compound
interest, and numbers of fowl, sheep, servants, and
gentlemen. The second volume of Mathematical

Repository (dedicated to David Papillon, of
Huguenot descent, Fellow of the Royal Society,
who confronted numbers in practice as one of the
nine commissioners of the excise for England and
Wales) introduces the doctrine of chances, the
author of which (rather, of the first system of this
doctrine in English), Dodson pointed out, was still
living and was, of course, De Moivre. Of the many
problems addressed by Dodson none was so interest-
ing to his British readers as the problem of annuities
and their reversions. That was understandable
given the "great property invested in them": the
"values of the possessions, and the reversions, of
much the greatest part of the real estates in these
kingdoms, will, one way or other, depend on the
values of lives." In the year before, in a paper in
the Philosophical Transactions, Dodson observed
that the determination of property was of too great
a practical importance to be left to "custom" and
was properly the business of "calculation." The
problem had been treated by Halley and soon after
by De Moivre with his "truly admirable hypoth-
esis, that the decrements of life may be esteemed
nearly equal, after a certain age." Another of
Dodson's publications was the Anti-Logarithmic
Canon, designed to assist the serious calculator, a
table of eleven-place anti-logarithms together with
examples of its uses in interest, annuities, men-
suration, and so forth. Mathematics was indeed
useful, and logarithms were the greatest modern
discovery in the "useful sciences," 35 according to
Dodson, one of the most active proponents of the
mathematics-of-life of the first half of the
eighteenth century.

'' Thomas Birch. "Memoirs of the Life of Martin Folkes Esq.
Late President of the Royal Society," BL Add Mss 6269, ff. 292-301.
quotation on f. 500; Martin Koikes. .1 Table of English Silver Coins from
the Norman Conquest to the Present lime. With Their Weig/its, Intrinsic
Values, and Some Remarks upon the Several Pieces (London. 1 745).

"Newton to Nathaniel llawes. Treasurer to Christ's I lospital, 25
May 1694. in The Correspondence of Isaac Newton, vol 3, ed. II. W. Turn-
hull (( lambridge: Cambridge University Press. 1961 ), 557-67, on 358.

"James Dodson, The Mathematical Repository. Containing
Analytical Solutions of hive Hundred Questions, Mostly Selected from
Si aire and Valuable Authors. Designed to Conduct lieginners to the More
Difficult Properties of Numbers, 5 vols. (London, 1748-55), quotation
on 2:viii; James Dodson. "A Letter ... Concerning an Improvement
of the Hills of Mortality," PT 47 (1752): 333-40, on 555; The Anli-
I .ogarithmic Canon. lieing a Table of Numbers Consisting of Eleven Places
of f igures. Corresponding to All Logarithms under 100000 (London,
1742), quotation from the dedication. Various letters and editorial
notes in 'The Correspondence of Isaac Newton, ed. II. W. Turnbull, vol. 2
(Cambridge: Cambridge University Press, I960). 575-77. Taylor,
Mathematical Practitioners of Hanoverian England, 174.

Science

The next youngest of De Moivre's pupils,
George Lewis Seott, was, like Papillon, one of the
commissioners of excise and so a man of quantity
and, as well, a barrister. Scott is remembered for his
mathematical skill and his advice to his friend, the
future author of Decline and Fall of the Roman
Empire. Early in life, Edward Gibbon formed a
new plan of study, hesitating between mathematics
and Greek; upon consulting Scott ("a pupil of De
Moivre," Gibbon noted in his autobiography), he
gave his preference to Greek; Scott's "map of a
country," by which Gibbon meant mathematics,
"which I have never explored may perhaps be
more serviceable to others." Upon reading the
proofs of the first volume of Decline and Fall, Scott
reassured Gibbon that when the book came out its
readers would not be shocked, but they were.
From his election in 1737, Scott was active in the
Royal Society, and though he did not publish any
mathematics in the Philosophical Transactions, he
kept up his interest in mathematics privately.
Naturally, he was drawn to the doctrine of chances:
in a letter to Folkes, Scott wrote that "Matters of
Chance are fertil in paralogisms," and the question
Folkes had "mentioned the other Day about Whist
has furnished me with examples enough." Scott
provided Folkes with two sheets of probability
calculations 36 and by that gift paid an implicit
compliment to De Moivre.

The De Moivre pupils Charles Stanhope
and Peter Davall were elected to the Royal Society
in 1726 and 1740, respectively. Stanhope served as
a Member of Parliament from a number of
constituencies, and he held offices accountable for
money (and was held accountable, being charged
and nearly convicted during the South Sea bubble
of using his office to make money on stock): under
George I he was treasurer of the chamber and
secretary to the treasury. 57 Davall published three
papers in the Philosophical Transactions dealing with
the sizes of cities, the distance of the sun, and an
extraordinary rainbow; he seems to have made his
mathematical services available to the Royal
Society. ,K John Colson published three mathematical
papers in the Philosophical Transactions, but his
importance lies in his teaching; like Saunderson, he
was Lucasian professor of mathematics, and as such
he enters our discussion of science at Cambridge.

Two of De Moivre's pupils were especially
important to the advance of science, the two aristo-

crats, George Parker, second earl of Macclesfield,
and Lord Charles Cavendish. Macclesfield's father,
as lord chancellor, was impeached by the House of
Lords under a long list of articles, which taken
together specify practically all the ways money can
be misused. Before that, at the time he was in-
stalled, he was given a pension for his son until his
son was old enough to become a teller for life of
the exchequer, which he became in 1719. Like his
father, Macclesfield studied law and became an
M.P., but his first love was always the mathematical
sciences. In addition to studying under De Moivre,
he studied under William Jones, and he may have
profited from still another Newtonian teacher,
since he, like Folkes, studied at Clare Hall when
Richard Laughton was there. He was elected to the
Royal Society at age twenty-five, and he was
promptly elected to the council, serving while
Newton was still president. In 1752, the year he
succeeded Folkes as president of the Royal
Society, Macclesfield was instrumental in bringing
about a famous practical application of astronomy, a
change in the reckoning of history, the calendar.
Friends and fellow pupils of De Moivre assisted
him: Davall drew up the bill and made most of the
tables, and Folkes examined the bill. In the
calendar then in use, the new year began on 25
March, in the new style calendar, on 1 January; and
it corrected for the accumulated errors in the
calendar owing to the precession of the equinoxes
by a one-time elimination of eleven days in
September. Anyone who doubts the emotional
power, as well as the power to bewilder, of
numbers, has only to recall Macclesfield's unpopu-
larity, which was visited upon the next generation;
when running for a seat in Oxfordshire, his son was
met by a mob crying, "Give us back the eleven
days we have been robbed of." Macclesfield's
private astronomical observatory was reputed to

^Joseph Timothy Haydn, Hook of Dignities: Continued to the
Present Time (I8V4). . . , 3d ed., ed. N. and R. McWhirtcr (Baltimore:
Geneological Publishing Co, 1970), 280-81. "Scott, George Lewis,"
DNB 17:961-62. The Autobiography of Edward Gibbon, ed. John
Murray (London. 1896), 191. D. M. Low, Edward Gibbon, 1737-1794
(London: Chatto & Windus, 1937), 262-63. Letter from George
Lewis Scott to Martin Folkes, 25 Apr. 1744. Royal Society Folkes
Corr., Ms. 250, f. IV, 26.

37 Ragnhild Hatton, George I, Ejector and King (Cambridge, Mass:
Harvard University Press, 1978), 255-56, 413.

'"Davall evidently refereed mathematical papers for the Royal
Society: Peter Davall to Thomas Birch. II Dec. 1754. BL Add Mss
4304. p. 128.

have the best equipment of any. He published
three papers in the Philosophical Transactions, one
on finding the time of Easter, one on an eclipse of
the sun, and one on the temperature of Siberia; his
importance for science was as an administrator and
patron. 39 Lord Charles Cavendish's quantitative
bent found its main outlet in experimental natural
philosophy. His importance for science was
primarily as an administrator, like Macclesfield, and
as mentor to his son I lenry Cavendish.

Royal Society

Early in June 1727, De Moivre's friend
W illiam Jones proposed the twenty-three year old
Lord Charles Cavendish for fellowship in the
Royal Society. Two weeks later, on 22 June,
Cavendish was formally admitted. 4 " At a meeting
of the executive council of the Society on that
same day, its president, Hans Sloane, raised the
question of qualifications for admission of new
members. By statute, as a son of a peer, Cavendish
was treated as if he were a peer and had to furnish
no proof of scientific achievement, ability, or even
interest. Under Fnglish law, however, the sons of
peers were commoners until they inherited the
family title. To raise the standards of membership
of the Society and reduce the exceptions to the
general rules of admission, Sloane proposed to treat
all commoners the same way with respect to
requirements. The issue came to a head a few
months later, in February 1728, when William Jones
proposed yet another son of a peer. The members
at large engaged in "Debates arising upon the
sense of the Statute w ith Relation to peers Sons
and privy Councellors whether any other
Qualifications of such Centlemen are required to
be mentioned or not. . . ." 41 In the end, the Society
changed some of its requirements for membership,
but it let stand those for peers and sons of peers. 4:

Flection to the Royal Society was the most
important event in Lord Charles Cavendish's
public life. For his son Henry it was decisive, for
without his father in the Royal Society, it is hard to
imagine the shy Henry entering science in any
public way and, perhaps, doing science at all.

Cavendish may have been a pupil of De Moivre
then, and he probably knew others of the circle who
were elected at about this time, such as De Moivres

Cavendish

friend Stirling, who was proposed in late 1726, and
his pupil Stanhope who was admitted then. 43

In 1727 Newton was still president of the
Royal Society, and when he was absent, Folkes or
Sloane took the chair in his place. Several members
of the governing council were Newton's friends
and, as we have noted, De Moivre's friends too.
I (alley, one of them, was especially active in the
scientific discussions at the meetings. Folkes,
Jones, and Bradley were on the council, as were the
two secretaries of the Society, the physician and
polymath James Jurin, a pupil of Newton's, and
John Machin, an astronomer who Newton thought
understood his Principia best of anyone, and who
with I lalley and Jones had been appointed to the
committee on the discovery of the calculus. Other
council members who had a close association with
Newton were Richard Mead, physician and author
of a Newtonian doctrine of animal economy,
Thomas Pellet, a physician who with Folkes
brought out an edition of Newton's Chronology of
Ancient Kingdoms in the year after Newton's death,
I Ienry Pemberton, who edited the third edition of
Newton's Principia, and John Conduitt, husband of
Newton's niece. Hans Sloane was a physician,
natural historian, and good friend of Newton and
I lalley. Like Sloane, several members of the
council were physicians with scientific interests:
John Arbuthnot, Paul Bussiere, James Douglas, and
Alexander Stuart. Roger Gale was a commissioner
of excise. The one peer, Thomas Foley, who was
repeatedly elected to the council, had an observa-
tory at his country seat near Worcester, from w hich
observations were sent to the Royal Society from
time to time. Two members of the council repre-

W'Parker, Thomas, first Karl of Macclesfield." DNB 15: 278-82,
on 280. "Parker, George, second Karl of Macclesfield," D.XH 15:
234-35. Collins's Peerage of England; Ceneo/ogiea/, Biographical, and
Historical, 9 vols., ed. E. Brydges (London. 1812) 4:192-94.
Macclesfield, then George Parker, was at (Hare Hall apparently
under the care of Francis Barnard, who reported to his father in 1716
on his progress; in the same year. Richard Laughton reported to
Macclesfield's father about a college election. Catalogue of the Stove
Manuscripts in the British Museum, vol. 1 (London, 1895), 548— 19.
Charles Richard Weld, A ///story of the Royal Society vol. 1 (New-
York: Arno Press, 1975), 432. In addition to Davall, James Bradley
also examined the calendar bill and made some of the tables for it.
Miscellaneous Works and Correspondence of the Rez: James Bradley, I). I).
F.R.S., ed. S. P. Rigaud (Oxford: Oxford University Press.' 1832),
Ixxx-lxxxii.

«°Royal Society, JB 13:103 and 107(8 and 22Junc 1727).

*'Royal Society. JB 13:175 (8 Feb. 1727/28).

«Weld, History 1:461.

"Royal Society, JB 13:1 (27 Oct. 1726).

ghled m aerial

Science

sented a distinctive British contribution to science
in the eighteenth century, the making of scientific
instruments. They were John Hadley, who was first
to develop the reflecting telescope that Newton
had introduced and who later introduced a
reflecting octant (based on a proposal by Newton),
and George Graham, to whom Bradley later said
that his own success in astronomy had " principally
been owing." 44 The governance of the Royal
Society was entrusted to the makers of scientific
instruments as well as to their users and to a good
number of able mathematicians. This diversified
and, by and large, eminent group of scientific men
on the council enlarged Cavendish's world in 1727.

That year was an auspicious year to enter
science. Vegetable Staticks, published by Stephen
Hales in 1727, was the most impressive demon-
stration yet of the promise of Newton's philosophy
to elucidate a new domain of facts. Educated at
Cambridge, where he began experimenting on
animal physiology, Hales continued his scientific-
studies while earning his living as a provincial
cleric. Hales's great inspiration was Newton's
Optkks, to which Newton appended his speculations
about forces of attraction and repulsion between
particles, with the help of which 1 lales inv estigated
the composition of plants and the air "fixed" in
plants. In early 1727 the chapter of his book on air
was read to the Royal Society, after which
Newton's handpicked experimenter Desaguliers
repeated many of Hales's experiments before the
Society. Hales had gone beyond his original
enquiry into plants to conclude that air is in "all
Natural Bodys" and is "one of the Principal
Ingredients or Elements in the Composition of
them." His experiments on fixed air laid the
foundations of pneumatic chemistry, the field in
which Lord Charles Cavendish's son Henry would
make his greatest reputation. The full importance
of Vegetable Staticks could not have been foreseen —
it was to encourage a generation of experimental
philosophers — but it was already appreciated, and
Hales was made a member of the council of the
Royal Society at the next election, at the end of
1727. Newton, who had presided during the final
reading of Hales's chapter on air, died five weeks
later, just shortly before Desaguliers' demonstra-
tion of experiments from that chapter. 45 The new
member of the Society Lord Charles Cavendish
was attracted to the physical sciences, to which

Hales's experiments on air came to be attached (and
detached from their origin in plant physiology). 4 ''

Meetings of the Royal Society varied greatly
in content and level of interest. On 8 June 1727,
the day Cavendish was elected to the Society,
Desaguliers performed another of Hales's experi-
ments. Two weeks later, on the day he was admitted
to the Society, Folkes brought in, and read about,
tusks. 47 To appreciate Lord Charles's continuing
education in science, we turn to matters that came
up in the meetings at the time he began attending.

We begin with practical schemes. In 1627,
exactly one hundred years before Lord Charles
Cavendish entered the Royal Society, Francis
Bacon's scientific Utopia, New Atlantis, was published.
Salomon's House, Bacon's projected cooperative
scientific college, was the original inspiration for
the Royal Society, which adopted the goal of
Salomon's House, the "effecting of all things
possible." The expectation was that the Royal
Society, like Salomon's House, would advance
human welfare through knowledge. That one
hundred years after New Atlantis the claims for the
utility of a scientific society could still be seen as
belonging to the realm of Utopia is shown by a
savage satire on the Royal Society. Just two years
before Cavendish was elected to the Royal Society,
Jonathan Swift wrote the third book of Gullivers
Travels, in which the Royal Society, renamed the
Academy of Lagado, labors to extract sunbeams
from cucumbers to warm the air on cold days. The
source of this ridicule was, evidently, Hales's recent

■"Bradley's words, from 1747. in Taylor, Mathematical Practitioners
of Hanoverian England, 120-21.

4, Stephen Hales. Vegetable Staticks: Or. an Account of Some Statical
Experiments on the Sap in Vegetables. . . Also, a Specimen of an Attempt to
Analyze the Air . . . (London, 1727). Henry Guerlac, "Hales. Stephen."
DSB: 6: 35-48, on 35-36, 41—4.?. References to the reading of Hales's
discourse on air and to Desaguliers' repetition of experiments from
it, in Royal Society, JB 13:44 (2 Feb. 1726/27). 45 (9 Feb. 1726/27),
48-50, quote on 48-49 (16 Feb. 1726/27), 70 (13 Apr. 1727), 74 (20
Apr. 1727), 83 (4 May 1727), 103 (8 June 1727), 144 (16 Nov. 1727).
Newton's death eaused the cancellation of the Society's meeting on
23 March 1726/27: Royal Society, J B 13:62.

4,, Insofar as publication in the Philosophical Transactions is a
measure, the physical sciences were a serious but not dominating
concern of the Royal Society at the time Cavendish was elected to
it. What we might call greater physics, including mechanics,
meteorology, and various border subjects of our modern physics,
accounted for about a third of the papers appearing in the
Philosophical Transactions. The absolute numbers of papers are very
small. John L. Heilbron, Physics at the Royal Society During Sexton's
Presidency (Los Angeles: William Andrews Clark Memorial Library.
1983), 43.

"Royal Society, JB 13:103 and 107 (8 and 22 June 1727).

Cavendish

experiments on plant and animal respiration. To
Swift, who was disgusted by everything the Royal
Society stood for. Bacon's optimism, projects,
experiments, the Newtonian philosophy, the
disparity between a Utopian faith and the reality of
life was self-evident. Whatever its logic, however,
Swift's satire was lost on the world of science. At a
meeting three months before Cavendish entered
the Royal Society, a letter was read from the
secretary' of the newly founded academy at
Petersburg, giving the plan of the academy, which
largely followed that of the academies at Paris and
Berlin, which in turn had profited from that of the
original, the Royal Society of London. Moreover,
like its predecessors, the Petersburg academy
would be interested in cultivating learning and as
well in improving medicine and encouraging
inventions. 4 " Observers as intelligent as Swift could
disagree with Bacon. To us, looking back, it seems
doubtful that Bacon's inspiration did anything
directly to advance technology, but it seems
equally likely that it did stimulate scientific
activity. The proceedings of the Royal Society
would seem to bear this out.

The Royal Society did not distinguish
between basic scientific understanding and its
applications, as is evident from the examples that
follow. The first is from medicine and public
health. Inoculation against smallpox, which had
long been practiced in the Hast, had just been
introduced in Britain when Cavendish entered the
Royal Society. The eminent London physician and
secretary of the Royal Society James Turin
enthusiastically supported it in the face of opposi-
tion from doubting physicians and clerics. The
operation did carry risk to the community as well as
to the patient, but so did this disfiguring and killing
epidemic disease, and Jurin argued with figures
that the risk of inoculation was less than that of
exposure. In the second year, the royal children
were inoculated (after the operation had been tried,
at royal request, on several condemned criminals,
without loss of any). In time inoculation came to be
widely practiced in Britain, if more so in the
countryside than in the cities. (Deaths by smallpox
continued to figure large in London bills of
mortality throughout the century; it is not known if
Lord Charles and I lenry Cavendish were inoculated
but only that they escaped or survived this scourge.
At the time Lord Charles left London for his first

visit to Paris, his sister Lady Elizabeth wrote that
"the small pox continues here very fatal." 49 )

Inoculation was based on an empirical
observation — a mild form of smallpox often
prevented a serious infection — which insured that
it would become a topic of interest in the Royal
Society. From far and near, Jurin received reports
of inoculations written up methodically in columns,
like weather reports, with which they had a
connection. The cause engaged other Fellows of
the Royal Society too, such as the physician who
inoculated the seven condemned criminals, Richard
Mead, who in 1727 was appointed physician to the king
and reelected to the council of the Royal Society.
The subject of smallpox inoculation recurred in the
meetings of the Society in 1727, and controversial
as it was at the time, it offered a glimpse into
Baconian paradise to those who believed. Despite
Jurin's best efforts, in Britain inoculation fell into
disfavor owing to deaths in prominent families. It
revived in the 1740s as a remunerative surgical
practice, but the true paradise began to be realized
only at the end of the eighteenth century, when the
English physician Fdward Jenner introduced
cowpox vaccination, the safe method of controlling
smallpox, which he came upon in the course of his
practice of giving original smallpox inoculations.
(George III, who was roughly Henry Cavendish's age,
was given Jenner's cowpox vaccination.) Medicine was
a large concern of Lord Charles Cavendish's Royal
Society, and although it did not happen to be one
of his own, he was an active and long-time gover-
nor of the Foundling Hospital where his good friend
William Watson regularly gave smallpox inocula-
tions and where he made an important scientific in-
vestigation of competing methods of inoculation. 50

Technology too was a concern of the Royal
Society in the early eighteenth century. For industry

♦"Francis Bacon. .Ym" Atlantis, published 1627. Jonathan Swift,
Gulliver's Travels and Other Writings, cd. M. K. Starkman (New York:
Bantam Books, 1962), 177. Royal Society, JB 13:52 (2 Mar. 1726/27).

w Lady Elizabeth Cavendish to Lord James Cavendish, 24 Apr.
/1721/. Devon. Coll., no. 166.1.

"Royal Society JB 13: I4S (7 Dec. 1727), 191 (7 Mar. 1727/28), 198
(21 Mar. 1727/28). 210 (11 Apr. 1728). "Jurin, James," DNIi 10: 1117-18,
on 1118. Leonard G. Wilson, "Jenner, Edward," DSB 7: 95-97, on 96.
William H. McNeill, Plagues and Peoples (New York: History Book
Club. 1993: first published 1976), 249-50. After 1800, smallpox
mortality in London fell to one half of what it had been in the
eighteenth century. Charles Creighton, A History of Epidemics in
Britain. Vol. 2: From the Extinction of the Plague to the Present Time, 2d
ed. (London: Frank Cass, 1 965 ), 479-8 1 , 504, 568.

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and for domestic heating, coal was increasingly
essential, since the forests were becoming depleted
and with them the alternative to coal, namely,
wood and charcoal. Mining was hazardous because
of the accumulation of unbreathable and in-
flammable air in the pits. Two weeks before
Cavendish's election to the Royal Society, its
curator of experiments, Desaguliers, reported on
his invention to remove unhealthy air from mines.
With a working model of it, one inch to the foot, he
gave a demonstration, which he called the Sir
Godfrey Copley's Experiment. 51 (This was the
annual experiment named after a benefactor of the
Society; four years later, in 1731, Copley's legacy
would be used to fund the Copley Award, which
both Lord Charles and Henry Cavendish would
receive for their scientific work.)

Britain was a maritime country, to which
fact the Royal Society was constantly being
recalled. Ships were lost or delayed because
navigators did not know their position relative to
the neighboring land. Nicolas Fatio de Dullier,
Newton's close friend, presented the Society with a
theorem for calculating latitude at sea and a copy of
his book on the subject, Navigation Improved.
Latitude could be known by taking the altitude of
the sun or a star, but longitude was not that simple.
The Greenwich Observatory was founded in 1675
to perfect astronomical tables for finding longitude,
but the tables did not work for ships. To secure the
safety of ships and to promote trade, in 1714 parlia-
ment passed an act providing rewards for improve-
ments in taking longitude at sea proportional to
their accuracy. The ultimate reward, 20,000 pounds,
a fortune, was to be paid to the discoverer of a
method that could, on a six-week journey to the
West Indies, give the longitude upon arrival within
an accuracy of thirty miles. To evaluate proposals,
the Board of Longitude was established, with
Newton on it. The Board was quickly innundated;
before a parliamentary committee, Newton rejected
all of the proposals, which added glory to fortune as
an incentive to future inventors. The Royal Society
was brought in as a source of expert opinion on
proposals, and Lord Charles Cavendish advised on
the marine clocks submitted by the man who
eventually won (nearly) the jackpot, John Harrison.
Joining science, invention, and utility, the problem
of longitude at sea made an ideal subject for the
Royal Society, where it came up repeatedly around

the time of Cavendish's election. Halley, for example,
a commissioner of the Board of Longitude and
champion of an astronomical method of deter-
mining longitude at sea, criticized a book on
longitude referred to him by the Society: the
author, Halley said, made two mistakes, one in
thinking his method was original, the other in
assuming what did not yet exist, "a true Theory of
the Moons Motion." For Halley, what was needed
for the astronomical solution of the problem was
more science. There were as well other practical
problems of the sea, such as measuring its depth
and mapping its coasts, and the Royal Society
heard about them all. 52

The atmosphere of the earth was another
kind of sea, with problems as daunting. In 1724, in
the name of the Royal Society, James Jurin had
invited meteorological observations kept according
to a plan, and around the time of Cavendish's
election, the Society was receiving weather journals
from abroad in considerable numbers. These
systematic observations of everyday weather were
in addition to the usual occasional observations of
the spectacular events of the atmosphere, great
cold spells, aroras, and the like." The weather was
one of Lord Charles Cavendish's major scientific-
interests, as it would be Henry's later.

Like Hales's fixed air, electricity at the
beginning of the eighteenth century was a
relatively new field of experimental study.
Electricity had no immediate utility, but it did pose
scientifically intriguing questions. Desaguliers
alternated his demonstrations of Hales's experiments
on air with experiments on the communication of
electrical virtue to a glass tube as shown by the
attraction and repulsion of fibers of a feather and of
gold leaves. Within a year of Cavendish's election,
Desaguliers announced that Stephen Gray in-
tended to bring before the Society experiments
showing that rubbed glass communicates its electrical

51 Desaguliers published the experiments on his model pump lor
damps: "An Attempt Made Before the Royal Society, to Shew I low
Damps, or Foul Air, May Be Draw n Out of Any Sort of Mines, etc. by
an Engine Contriv'd by the Reverend J. T. Desaguliers, L.L.D. and
F.R.S.," PT 34 (1727): 353-56.

"Royal Society, JB 13:168-69 (25 Jan. 1727/28), 84 (II May 1727),
1 13 (29 June 1727), 302 (4 May 1727), 214 (2 May 1728), 232 (20 June
1728), 287 (23 Jan. 1728/29). I lumphrey Quill, John Harrison: The Man
Who bound Longitude (London: John Baker, 1966), 1-6.

"Royal Society, JB 13:34-36 (12 Jan. 1726/7), and many other
places.

Cavendish

c|iiality to any body connected to it by a string. 54 It
is indicative of the state of electrical knowledge
that Cray was the first to describe explicitly
electrical conduction and to distinguish between
conducting and non-conducting bodies. Lord
Charles Cavendish would take up this new field of
electrical conduction, and Henry Cavendish would
work out its basic laws.

The full range of topics discussed at the
Royal Society around 1727 was, of course, much
greater than these examples suggest. From the side
of medicine, there were reports on stones, cataracts,
and aneurisms. There were accounts of coconuts,
cinnamon, and poison snakes from the side of
natural history (and from the far-flung British
colonies). Fossils and other natural collectibles and
curious specimens were displayed at the meetings.
Two-headed calves and various other monstrous
productions were as common at the Royal Society
as they were uncommon in nature. Fellows
travelling abroad wrote home or brought back
information about everything having to do with
science. Investigative natural reporting of singular
disasters such as earthquakes was given as often as
opportunity permitted. Correspondence was read,
books were received, guests were introduced, and,
in general, the Society served its members as a
great clearing house for scientific news. Except for
the formalities, the meetings were kept lively by
the variety of their proceedings. Here is a typical
offering. John Byrom, Fellow of the Royal Society
and frequent attender, noted in his journal persons
and topics at the meeting on 27 February 1728/29:
"Vernon there from Cambridge; Dr. Ruty read
about ignis fatuus; humming bird's nest and egg,
mighty small; Molucca bean, which somebody had
sent to Dr. Jurin for a stone taken out of a toad's
head; Desaguliers made some experiments about
electricity." 55 That night there was something for
just about ev erybody, and Byrom ran it all together
in his journal. Within the Society there was a kind of
democracy of interests. When one interest was per-
ceived to be systematically favored, allegations could
fly; I lenry Cavendish would be caught up in them.

When Lord Charles Cavendish became a
Fellow, the Society wore two crowns, one scientific,
one royal. We begin with the scientific. Newton
had just died, but he lived on in the causes that
continued to be championed in his name. Thomas
Derham wrote to the Society from Rome about a

book by an Italian that "pretends" to refute propo-
sitions in Newton's Opticks; Desaguliers responded
to the perceived danger. The dispute over whether
the measure of force is the velocity, as Newton
said, or the square of the velocity, as foreign mathe-
maticians said, was settled by Desaguliers (he
thought) by experiment and was adjudicated by
Jurin, who regarded it as a mere dispute arising
from an ambiguity in the meaning of the word
force. Andrew Motte presented to the Society his
English translation of Newton's Principia, and William
Jones was asked to look it over and give the society
an account of it. 56 As to the royal crown, in the year
Newton died and Cavendish entered the Society,
King Ceorge I died, and his successor to the
throne, Ceorge II, agreed to succeed him as well in
the role of patron of the Royal Society. The change
in monarchs entailed considerable ceremony and
protocol, the carrying of the charter book to St.
James's for the royal signature, the making of an
address, the paying of compliments to the queen.
There was also a change of heir to the crown. The
new prince of Wales, Frederick, became a member of
the Royal Society, an honor which was commem-
orated by the dedication to him of the volume of
the Philosophical Transactiotisfot 1728. That year Lord
Charles Cavendish became gentleman of the bed-
chamber to Frederick. 57

Below the rank of royalty, but not far, within
the dukedom of the Devonshires, another suc-
cession was about to occur. But for the time being,
as Charles Cavendish entered the Royal Society,
his father, the second duke of Devonshire, was still
alive and the owner of a great loadstone, supported
in a fine mahogany case and raised by screws,
which came up in discussion at the Royal Society a
few months after ( lavendish was elected. This magnet
had prodigious force, as Folkes bore witness,
having seen it lift "more than its own weight." 58 In
1730 the magnet was produced again, this time by

S4 Royal Society, JB 13: 307 (27 Feb. 1728/29), 316 (13 Mar.
1728/29). 330(1 May Ml 1 )).

"John Byrom, The Private Journal and Literary Remains of John
Byrom, ed. R. Parkinson, 2 vols, in 4 parts (Manchester. 1854-571,
vol. I. part I, p. 534 (27 Feb. 1728/29).

5»Royal Society, JB 13: 175-76 (8 Feb. 1727/28). 242 (4 Julv 1728),
251 (24 Oct. 1728). 252 (31 Oct. 1728), 257 (7 Nov. 1728), 262 (14 Nov.
1728), 339-40 (22 May 1729), 341 (5 June 1729).

"Royal Society, JB 13:86(11 May 1727). 114(6 July 1727).

SH Royal Society, JB 13:314 (13 Mar. 1728), 18:400(25 Apr. 1745).
W illiam Dugood. F.R.S., who built this magnet for the duke, built an
even bigger one for the king of Portugal.

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Desaguliers, who showed the Society experiments
with it including lifting 175 pounds. 59 With this,
the "famous Great Loadstone of his Grace the
Duke of Devonshire," we conclude our account of
Lord Charles Cavendish's introduction to the
Royal Society. This magnet, with its remarkable
powers, might be taken here to have a double
meaning, physical and political, and to imply, if
fancifully, a third and prophetic scientific meaning
through the duke's son and grandson, Lord Charles
and Henry Cavendish.

Later we take up Lord Charles Cavendish's work in
science, but here we should mention his earliest
recorded observations and their circumstances. More
or less coinciding with his election to the Royal
Society, they foretell the kind of member he will be.

Although the experimental fields of
pneumatic chemistry and electricity were under-
way around the time Lord Charles Cavendish
joined the Royal Society, the incontrovertible
achievements in the physical sciences continued to
be in the exact sciences. Cavendish began his
scientific work in conjunction with James Bradley,
a practicing astronomer of world renown, who was
on the eve of his momentous discovery of the
aberration of light from the stars.

In June 1728 Cavendish made zenith
observations at Bradley's observatory at Wansted
with a telescope for detecting the parallax of the
fixed stars. 60 The instrument had been in place for
less than a year, and after Bradley himself, and
then Halley, Cavendish was the next person to
observe with it. Later that year, in the course of
looking for the parallax, Bradley made his dis-
covery of the aberration of light.

This was a great discovery. With his new
instrument Bradley observed the small motions of
stars passing nearly through the zenith, motions
which he knew were too large and in the wrong
direction to be caused by the parallax of the fixed
stars. In 1729 Bradley had found the answer: the
motion of the zenith stars was the resultant of two
motions, that of the orbital motion of the earth and
that of light. In his announcement of Bradley's

discovery of the aberration of light to the Society,
Halley remarked that the "three Grand Doctrines
in the Modern Astronomy do receive a Great Light
and Confirmation from this one Single Motion of
the Stars Vizt. The Motion of the Earth. The
Motion of Light and the immense distance of the
Stars." Bradley had, in fact, provided the first direct
evidence of the motion of the earth, i.e., of the
Copernican theory, and twenty-four year-old Lord
Charles Cavendish had had a connection, however
slight, with this great work of observation and
reasoning in astronomy/' 1

Cavendish's observations at Wansted are only the
first of his many connections with Bradley. This is
the appropriate place to cite another, since it brings
together Cavendish, Bradley, and members of the
De Moivre circle, the starting point of our discus-
sion of Cavendish in London science. Macclesfield,
father and son — the lord chancellor and the
president of the Royal Society — were patrons and
friends of Bradley throughout his life. In 1732
Bradley moved from Wansted to Oxford, which
was only a few miles from Macclesfield's home at
Shirburn castle. There, in Macclesfield's observa-
tory, he and Macclesfield regularly made observa-
tions together. When Bradley became a candidate
to succeed Halley as astronomer royal, Macclesfield
exerted his influence, only he had to do it indirectly,
since his voting had put him out of favor with the
court. To build scientific support for Bradley,
Macclesfield wrote to William Jones to ask him to
enlist Folkes and Lord Charles Cavendish. Here,
at this important juncture in Bradley's career, we
come across a constellation of De Moivre 's friends
and pupils, now all prominent figures in the Royal
Society. 62

"Royal Society, JB 13:454 (9 Apr. 1730). The magnet remained
within the family, passing from the second duke to his brother Lord
James Cavendish. F.R.S.

"'Bradley, Miscellaneous Works, 2M.

'•' Roval Society, JB 1.1:260-62. quotation on 262 (14 Nov. I72X).

"Lord Macclesfield to William Jones, 13 Jan. 1741/42; Lord
Macclesfield to Lord Hardwickc, 14 Jan. 1741/42. in Bradley,
Miscellaneous Works, xlvi and xl\ ii, respectively.

CHAPTER 3

family and Friends

Marriage and Money

In January 1728/29, Lord Charles Cavendish
married Lady Anne de Grey, daughter of the duke
of Kent. Cavendish was very young, in his middle
twenties instead of in his middle thirties, a much
commoner age for younger sons of nobility to
marry. 1 He could afford to take this step in life
early because he was a son of the duke of
Devonshire and a son-in-law of the duke of Kent,
who had a lesser estate than the duke of
Devonshire, but who was ambitious for his family
and, in particular, for advantageous marriages for
his daughters. We know nothing of the affection
between Charles and Anne, but in any case,
wealth, rank, and respectability were probably the
governing considerations in this match.

Financial arrangements made at the time of
marriages within the nobility in eighteenth-century
England took a standard form. In each generation
the essential provisions for the family were settled
on the occasion of the eldest son's marriage, and
these were always directed to ensuring that the
family estate descended to him for his life. The
supreme object of favoring the eldest son was to
prevent the dispersal of the estate owing to whim,
greed, enmity, or debauchery, which meant that the
daughters and younger sons had to be helped
financially in ways other than by inheritance of the
family estate. In 1723 the lord chancellor,
Macclesfield, ruled that under the law, equity
placed younger children "on a level with creditors,
taking it to be a debt by nature from a father to
provide for all his children." 2 In practice, the
otherwise complete freedom of parents in providing
for the younger children was constrained only by the
assumption that the settlement would be sufficient
to allow the younger sons to live independently
and the daughters to marry well. The independence
of Lord Charles Cavendish and his brother Lord
James, the other younger son, was securely
established by the second duke of Devonshire. 5

It was standard for younger sons at the time
of their marriage or coming of age to receive capital
sums and often also annuities or rent charges.
Daughters at the time of their marriage were given
dowries, or portions, and in the event of their
husbands' deaths, widows were supported by annual
incomes, or jointures. Marriage settlements also
specified the fortunes that would go to the eventual
children of the marriage. Numbers of children and
combinations of sexes and possible orders of deaths
were all taken into account, as nothing in matters
of such importance was left to chance.

Like their parents' marriage settlement,
that of Lord Charles and Lady Anne conformed to
the pattern. It was customary for wives to provide
for their younger sons. Lady Anne's father, the
duke of Kent, at his death left 12,000 pounds to her
and through her to her children, 2,000 pounds to
the oldest child and 10,000 pounds to the others, in
this case, to the only younger child, Frederick.
Lord Charles's mother, Rachel, duchess of
Devonshire, had left the bulk of her personal
estate to him and to her other younger son, Lord
James. Lord Charles's marriage portion was 6,000
pounds in Bank of England stock, 2,000 pounds in
South Sea stock, and 4,000 pounds in South Sea
annuities, a total of 12,000 pounds on paper. From
her father, Lady Anne acquired her portion, 10,000
pounds. The two portions of 12,000 and 10,000
pounds, in the form of securities, were transferred
to trustees of the marriage settlement, who raised
1 7,000 pounds by the sale of the securities for the
purchase of the estate of George Warburton. This
estate consisted of three manors, Putteridge, Lilley,
and Hackwellbury, together with several farms.

'Lawrence Stone, I'lie Family, Sex and Marriage in England
1500-1H0Q , abr. cd. (Harmondsworth: Penguin Hooks. 1982), 42.

'Quoted in Randolph Trumbach, The Rise of the Egalitarian
Family: Aristocratic Kinship and Domestic Relations in Eighteenth-Century
England '(New York: Academic Press, 1978), 87.

'Ibid., 89-90.

Cavendish

located directly north of London, at about half the
distance of Cambridge, in the adjacent counties of
Bedford and Hertford. Putteridge Manor would
become the first and only home of Lord Charles
and Lady Anne. From her father. Lady Anne, as
one of four sisters, also received one quarter part of
his estate at Steane, the rents from which were
vested in trustees for Anne's separate use during
her marriage. She was also given the power to leave
these rents as she willed, and she left them (or
their equivalent in stock, as it turned out, since the
Steane estate was sold in 1744) to Frederick. The
married couple would have a home, Lady Anne's
personal expenses would be provided for, and the
children's needs anticipated. 4

What remained was for Lord Charles to be
assured an income that would enable him and his
family to live in appropriate comfort; this was seen
to by Lord Charles's father. Younger sons of the
aristocracy customarily received 300 pounds a year,
which is what Lord Charles had been receiving
from his father since 1725. 5 His father intended for
the annuity to be raised to 500 pounds at his death,
but he moved the plan ahead: starting in 172H, with
his marriage. Lord Charles would receive 500
pounds annually. In addition his father granted him
the interest on 6,000 pounds and eventually the
capital itself.''

That was not all. In eighteenth-century
society, in which "men were measured by their
acres," 7 nothing could compare with ownership of
land for imparting a sense of independence.
Following a practice that had been commoner in
the seventeenth century than in the eighteenth,
the second duke of Devonshire devolved property
(a crumb, relatively speaking) on Charles Cavendish
and his heirs. These were tithes, rectories, and
lands in Nottinghamshire and in Derbyshire.
Having been promised them in 1717, Lord Charles
received the rents in 1728 and the inheritance the
following year; the marriage settlement directed
that from these rents Lady Anne was to receive
one hundred pounds a year for their joint lives. At
the beginning the rents brought in over a thousand
pounds a year, and after the enclosures of the 1760s
and 1770s they increased considerably. Since for
some years to come, these rents would provide an
important contribution to Lord Charles's income,
he took good care of this property. There was one
last provision of the marriage settlement from

which Lord Charles would benefit: after the duke
of Kent died, in 1740, Lord Charles received
interest on 12,000 pounds left to Lady Anne's
trustees. From his mid twenties, Lord Charles
Cavendish could count on a disposable annual
income of between 2000 and 3000 pounds, and this
income grew steadily. To give an idea of what this
meant: Samuel Johnson, a professional man, who
rarely made above 300 pounds, thought that 50
pounds was "undoubtedly more than the
necessities of life require"; and a gentleman lived
comfortably on 500 pounds and a squire on 1000
pounds. Cavendish's income enabled him to live
very well indeed, invest in stock, and acquire
books and instruments and generally support his
scientific pursuits. It permitted his son Henry to do
the same, and, at the same time, it laid the
foundation of Henry's fortune. 8 Within the
conventional financial arrangements of wealthy
English families of the time, the Cavendishes and
the Greys combined to create what was in effect a
scientific endowment for Lord Charles and Henry
( lavendish.

Before his marriage, Cavendish evidently kept a
residence in Westminster.'' Immediately upon his
marriage, as we have seen, in February 1729 he

'Devon. Coll.. L/19/33 and L/5/69.

5 This financial detail would seem to settle the birthdate or. at
least, the year of birth of I ,ord ( )harlcs ( )avendish, on w hich we were
indefinite earlier. On 6 April 1725 his father gave him the annuity; we
think he was twenty-one on this occasion, which would suggest that
his birthdate was on or near 6 April 1725. But that is not right, since,
as we have pointed out. his mother was expecting a baby in July
1725. Lord Charles needed an income in April because he was about
to be returned as M.R for Hcytesbury on 15 April that year.

'The 500 pounds and 6,000 pounds were determined by a much
earlier family settlement, of 1678.

'J. II. Plumb. Men and Centuries (Boston: Houghton Mifflin.
1963), 72.

"Devon. Coll., L/5/69. L/13/8, L/19/20, L/19/31, L/19,33, L/78/2,
L/114/32. Charles Cavendish also received a legacy of 1.000 pounds
from his father: Chatsworth. 86/ comp 1. There is some discrepancy
between the description of the marriage settlement we give from the
legal documents and what Charles Cavendish jotted down in a short
abstract of the settlement, but it is minor: Devon. Coll.. L/l 14/74. H.
J. Habakkuk. "Marriage Settlements in the Kighteenth Century."
Transactions of the Royal Historical Society 32 (19501: 15-30. on 15-16.
18. 20-24. (ieorge Rude. Hanoverian London, 1714-1808 (Berkeley:
I Diversity of California Press. 1971 ). 48. 61.

''We know nothing about this residence other than that it was
probably substantial. Cavendish appeared on the poor rolls of
Westminster Parish of St. Margaret's in 1728; he paid 5.5.0
annually, which is what the duke of Kent paid and a c|uarter of
what the duchess of Devonshire paid. Westminster Public
Libraries. Westminster Collection, Accession no. 10. Document
no. 343.

CopynghiM material

Family and Friends

acquired the country manor of Putteridge and the
other manors and farms that came with it, from
which he would have received rents. In 1730 he
sold a rectory, which was appended to one of these
manors, Lilley, to the master and fellows of St.
John's College, Cambridge (with which college he
would later have scientific connections). There is
every reason to believe that he planned to stay at
Futteridge and raise his family there, in which case
if it had not been for his wife's early death, the still
countrified site of Futteridge would be hallowed
ground in the history of science.

When Lord Charles and Lady Anne moved
to Futteridge, Charles had an active life in the city,
in court, in politics, and in science; in 1729, the year
of his marriage, he had already begun to serve on
committees of the Royal Society. 1 " A portrait of
Lord Charles Cavendish shows a handsome young
man of slender build and medium dark com-
plexion, with a long, narrow face, a long nose, full
lips, prominent eyes, and an alert expression. We
have two portraits of Lady Anne, one of her
together with two of her sisters, and one of her by
herself and somewhat older. She is slender with a
round face, wide-set, intelligent eyes, high,
rounded eyebrows, and straight nose. At the time
of these portraits she was evidently in good health,
which was not to last.

There is evidence that Lady Anne was not
strong before her marriage," and in any case, in the
winter one year later, she was ill. Sophia, duchess
of Kent, her step-mother, wrote to her father, the
duke, that she had just dined at the Cavendishes:
"Foor Lady Anne does not seem so well as when I
saw her last. Her spirits are mighty low and she has
no stomach at all. She has no return of spitting
blood nor I don't think she coughs more than she
did so that I hope this is only a disorder upon her
nerves that won't last." 12 The next winter, 1730/31,
was bitterly cold, colder — William Derham, F.R.S.,
wrote to the president of the Royal Society — than
the winter of 1716, when the Thames froze over."
That winter, we believe, Lord Charles and Lady
Anne went abroad. From Paris Lady Anne wrote to
her father that in Calais she had been very ill with a
"great cold" and that she had been blooded and
kept low to prevent fever. She did not expect to
see much of Paris for fear of being cold, and in any
case they were about to leave the city for Nice. 14
Nice (where the yearly mean temperature is 60

degrees, in winter 49 degrees and in summer 72
degrees) was much milder than London, where —
to use Lord Charles's own, later twenty-year
averages — the mean minimum temperature in
January is 34.7 degrees and the mean minimum
temperature in July is 55.6 degrees (and the mean
temperatures, not minimums, are 37 degrees and
63.5 degrees, respectively). The combination of
sun and sea has given Nice a reputation for being
especially suited for people convalescing from
acute lung ailments. 15 In all likelihood, Lord Charles
and Lady Anne went there for the weather and the
waters because of Anne's health. They definitely
did not go as conventional tourists, for although
Nice did become popular with Knglish tourists,
that did not happen until the second half of the
eighteenth century. In 1731 Charles Cavendish was
the only Englishman to stay in Nice who did not
have commercial or diplomatic ties there. The only
permanent Knglish resident was the consul, who
did double service as an Knglish spy on the
French."' About three months after leaving Paris,
Lady Anne conceived. In Nice, on Sunday, 31
October 1731, she gave birth to her first child,
named after her father, Henry de Orey. No
birthplace could be less predictive: beginning life
in a sleepy Mediterranean town of about 16,000
inhabitants situated amongst olive groves, Henry

'"On 17 July \7Z') Cavendish was appointed to a committee to
inspect the library and the collections and deliver reports; it met
every Thursday from 24 July until 6 November 1729. and on II
December it was ordered to continue its work. Royal Society,
Minutes of Council 3:28-30, 34-36, 39, 55-56, 114-16.

"In the summer before Lady Anne's marriage, the house-
accounts for the duke of Kent repeatedly record "Chair hire for Lady-
Ann." None of the duke's other daughters required chairs then.
•Julv 1 728. Mouse Account. To y 28 December 1728," Bedfordshire-
Record Office. Wrest Park Collection. L 31/200/1.

,2 Sophia, duchess of Kent to Henry, duke of Kent. 21 Feb.
1729/30, Bedfordshire Record Office, Wrest Park Collection. L
30/8/39/3.

"William Derham, "A Letter . . . Concerning the Frost in
January, 1730/1," PT 37 (1731; published 1733): 16-18.

H Ladv Anne Cavendish to Henry, duke of Kent, 4 Nov. /1 730?/,
Bedfordshire Record Office, Wrest Park Collection. L 30/8/11/1.

""Nice," Encyclopaedia Hritannica (Chicago: William Benton.
1962) 16:414-15. Lord Charles Cavendish's twenty-year averages of
his readings of nighttime lows in London arc included in William
Heberden. "A Table of the Mean Heat of Every Month for Ten
Years in London, from 1763 to 1772 Inclusively," W78 (1788): 66.

"■Henri Costamagna, "Nice au XVIII* siecle: presentation
historic) lie et geographi<|iic," Annates de la baculle des Lertrts et Sciences
Humaines de Nice, no. 19, 1973, pp. 7-28. on p. 26. Daniel l-cliciangcli,
"Le developpement de Nice au cours de la secondc mnitie de
XVIII 1 siecle. Les anglais a Nice," ibid., pp. 45-67, on pp. 55-56.
Anon., Iss Anglais dans le C.omte de Sice el en Provence depuis le W ill""
siecle (Nice: Musee Massena, 1934), 72.

Cavendish

( lavendish grew up to be one of the most confirmed
I Londoners ever.

The next stage of Lord Charles and Lady
Anne's marriage is short and ends sadly. A year and
a half had passed since they had left Fngland, and
they were now back in France, in Lyon, from
where in the summer of 1732 she wrote to her
father about her health and happiness. It was with
her usual perfected penmanship, the letters large,
uniform, and inclined at precisely the same angle,
but her hand was unsteady, like that of an elderly
person. Nevertheless, her letter home begins with
reassurances: her fever had not returned, and she was
so far recovered that she and Lord Charles were
going to Geneva the next day, a three-day trip. If she
handled that well, they would stay there only two
or three days and then go directly to Leyden. She
did not know when they could return to Kngland.
Lady Anne closed the letter with word of her baby,
Henry. "I thank God," she wrote, "my boy is very
well and his being so very strong and healthy gives
me a pleasure I cannot easyly express." 17

The Cavendishes were going to Leyden to
sec the great teacher and healer Hermann
Boerhaave. Although Boerhaave was nearing the
end of his career at the University of Leyden,
where he taught medicine and, until recently,
botany and chemistry alongside it, in 1732 he was
still lecturing on the theory and practice of
medicine and giving clinical instruction. He had
written influential treatises on medicine and was,
by many accounts, the most famous physician in
the world, if not the most famous scientist since
Newton. His ties with British medicine and, in
general, with British science were particularly
close. From all parts of the world but especially
from Britain, students came to Leyden to attend
his lectures: of the nearly two thousand students
enrolled in Leyden's medical faculty, fully one
third were Fnglish-speaking. British physicians
who had studied under Boerhaave consulted him
when their treatment of aristocratic or otherwise
important patients had not worked. Prominent
British travelers went to Leyden to see Boerhaave,
often but not always about their health. 1 * For his
part, Boerhaave was a tremendous admirer of British
experimental philosophy and one of the first
exponents of Newtonianism in Furope. He was
elected to the Royal Society in 1730. For all these
reasons, it was natural for the well-informed Lord

Charles Cavendish to seek out Boerhaave's services
for his wife. Lady Anne told her father that they
thought it would be right for Dr. Boerhaave to "see
me pretty often in order to make a right judgment
of my illness." No other letters by her have been
found, so we do not know what Boerhaave said and
prescribed. 1 '' Tuberculosis was a common disease
for which medicine then, of course, had no cure.

At some point Lord Charles and Lady Anne
returned to Fngland. Three months after her
consultation with Boerhaave, Lady Anne was well
enough to conceive again, and on 24 June 1733 she
delivered another son, Frederick, named after his
sponsor, the prince of Wales. The next we hear is
that Lady Anne Cavendish died at Futteridge on
20 September I733. 20 She was twenty-seven. Henry
was not quite two years, Frederick was three
months, and Lord Charles was around twenty-nine.
In Lord Charles's station, remarriage was uncommon,
and he would live for fifty years as a widower.

Although for someone like Lady Anne Cav-
endish who liv ed into her twenties, life expectancy
was over sixty in the eighteenth century, life then at
any age was precarious. Hygiene was unknown,
medicine was helpless, and death was indifferent
to privilege. Henry and Frederick Cavendish grew
up with one parent, which was a common fate
under the prev ailing conditions of life. 21

Great i Marlborough Street

In 1738 Lord Charles Cavendish sold
Futteridge together with the rest of the estate
purchased by his trustees at the time of his
marriage. The deal was not straightforward though
it was not uncommon either. For the trustees to be
empowered to make the sale, an act of parliament
had to be passed, and for that, a reason had to be
given for wanting it. Futteridge, Cavendish said,

'"Lady Anne Cavendish to Henry, duke of Kent, 22 June /1 732/,
Bedfordshire Record Office, Wrest Park Collection. L 30/8/11/2.

'"A typical example from this time: Bolingbroke wrote to his
half-sister Henrietta from Totterdam: "I was yesterday at Leyden to
talk with Doctor Boorehaven, and am now ready to depart for Aix-la-
Chapelle . . ." Letter of 17 Aug. 1729, in Walter Sichel, Bolingbroke
and His Times: The Sequel (New York: Greenwood, 1968), 525.

'''(;. A. Lindeboom. lioerhaavt and Great liritaiii (Leiden: K. J.
Brill, 1974), IK; "Boerhaave, Hermann." DSB 2:224-28. .

-'"Four days later, on 24 Sep. 1733, Lady Anne Cavendish was
buried in the Kent family vault at Flitton. "F^xtracts from the Burial
Register of Flitton." Bedfordshire Record Office. Wrest Park
Collection. L 31/43.

"Stone, Family, 46-48, 54. 58-59.

Family and Friends

was too remote from the rest of his estate, whatever
he meant by that. No doubt he wanted to move
into the city, where his political and scientific life
lay. Parliament directed the trustees to sell the
estate for the best price possible. 22

It would seem that Cavendish got about
what was paid for the estate, 23 which was 17,000
pounds, and the house he bought in its place that
same year, 1738, cost only one tenth that: for the
absolute purchase of a freehold in Westminster, he
paid 1,750 pounds. The location was near Oxford
Road, at the corner of Great Marlborough and
Blenheim, both streets named to commemorate a
military action of the duke of Marlborough in 1704.
Victories like the one at Blenheim had, in fact,
assured the conditions of life for the kinds of
persons who lived on Great Marlborough Street,
namely, gentlemen and tradesmen, evenly balanced.
In appearance Great Marlborough Street was, and
is, an atypical London street, long, straight, and
broad. Admired for its Roman-like grandeur, it had
its drawbacks too. The street opened onto no
vistas, and its houses, though solid, were undistin-
guished. Now all demolished, the houses gave the
street a uniform appearance, though the house that
Cavendish bought, number 13, was unusual in one
respect. It was, in fact, two houses (the setting for
this dual biography), which had been joined
around 1710 when John Richmond, who had
actually fought at Blenheim and had risen to the
rank of general, leased the then two separate
houses. Following the general's death in 1724, the
house went on the market as two houses-in-one.
From a newspaper advertisement the next year, we
get an idea of its size and layout. The property
extended forty-five feet to the front, and in depth
two hundred feet, accommodating a spacious garden,
at the end of which an apartment had been built
with a communication to the house. There is reason
to think that later on Henry Cavendish made use
of this apartment, which had a kitchen underground
and living quarters, consisting of four rooms, on the
one floor above. To some degree Lord Charles and
the adult Henry maintained separate establishments
in the same house; they had separate silver, for
example. 24 Naturally, the property also had stabling
and coach houses. The spaciousness of the buildings
and of the garden were important for the life of
science that was lived there; for like the house, the
life of science was double too. Here, on Great

Marlborough Street, Lord Charles Cavendish would
live the rest of his life and Henry Cavendish most of
his, and here they, together and singly, would carry
out experimental, observational, and mathematical
researches in all parts of natural philosophy.- 5

Two years after Lord Charles Cavendish bought
the house on Great Marlborough Street, in 1 740 an
opening was created by death on the local governing
body of the parish, the vestry of St. James,
Westminster. Cavendish was elected to fill it. His
father-in-law, the duke of Kent, who had been a
vestryman in the parish, had just died, and he too
was replaced at the same time, by another duke.
The vestry dealt with every kind of practical
problem of civil life: road repair, paving, night watch,
workhouses, petitions for the commons, rates, levies,
grants, and accounts. No detail was too small; the
vestry approved a new umbrella for ministers
attending burials in the rain. It was characteristic of
Cavendish to turn up faithfully at vestry meetings,
held as needed, roughly once a month. A few other
members attended as regularly too, and these he
was either related to, such as Philip Yorke, or met
with on boards of other institutions, such as
Macclesfield from the Royal Society. Cavendish
served his parish for thirty-three years, attending
his last meeting in early 1783, just before he died. 2 ''
The wider setting for the scientific drama that took

""An Act for Discharging the Estate Purchased by the Trustees
of Charles Cavendish . . . from the Trusts of his Settlement, and for
Enabling the Said Trustees to Sell and Dispose of the Same for the
Purposes Therein Mentioned." Devon. Coll.

"Devon. Coll., L/l 14/32.

J4 In the year before his father died. Henry Cavendish took a
house in Hampstead. That year he made an inventory of silverware,
plates, pans, coffee pots, lamps, and so on: beside many entries, he
wrote "CC," and beside other entries "H," standing, we suppose, for
Charles Cavendish and for Henry. "An Inventory of Silver Plate
Belonging to the Hon hlc Henry Cavendish Delivered to the Care of
Geo. Dobson Feb' the 7th 1782," Chatsworth, 86/comp. 1.

-'"Assignment of Two Messuages in Marlborough Street from
the Honorable Thomas Townshend Ksq to His Right Hon hlc Lord
Charles Cavendish," 27 Feb. 1737/38, Chatsworth, L/38/35. London
County Council, Survey of London, vol. 31: The Parish of St. James
Westminster. Hart 2: North of Piccadilly, gen. ed. T. II. W. Sheppard
(London: Athlone. 1963), 251-56.

^Minutes of the Vestry of St. James, Westminster, D 1760-1764.
Westminster City Archives, from his election to the vestry on 26 Dec. 1740
(D 1760, p. 145) to his last meeting on 13 Feb. 1783 (D 1764. p. 518). With
the vestry men, ( jvendish had other duties in the parish; he was a trustee,
for example, of the King Street Chapel and its school and met with other
trustees at the end of year to pass the accounts. Great Britain. I listorieal
Manuscript Commission, Manuscripts of the Earl of Egmont, Diary of the
First Earl of E.gmont, Viscount Percival. vol. 3 (London: His Majesty's
Stationary Office, 1923), 270 (4 Jan. 1742/3), 306 (4 Jan. 1744/5). King
Street ( :hapel was also known as Archbishop lenison's ( lhapel, King St.

Cavendish

place on Great Marlborough Street was greater
London, which included Westminster. At around
the time Cavendish bought his Westminster house,
one sixth of the people of England either lived or
had once lived in greater London. In his son
Henry's lifetime, owing to an influx from the
provinces and from abroad, its population swelled
to nearly a million. Whereas the filth, poverty, and
drunkenness of eighteenth-century London are
faithfully depicted in Hogarth's prints, the city's
lure is equally well depicted in Boswell's London
journals. London was wealth, power, and patronage,
an opportunity to rise in the world. London was
the seat of national government, a great port city,
the commercial center of a colonial system,
headquarters of great trading companies, and the
financial capital of the world. Whether a Londoner
w as rising or was, like a Cavendish, already at the
top, he was in the presence of every convenience
known to civilization. Westminster could boast of
almost four hundred distinct trades, among which
w ere trades of special interest to Lord Charles and
I lenry Cav endish, such as the instrument and book
trades. The resident of London was in the center
of the world; yet whenever he felt that the world
was too much with him, he had only to step back
out of the street to find himself inside his own
house, his castle "in perfect safety from intrusion."
For a man who was interested in the great world
and yet was a shy homebody like Henry Cavendish,
it was no small recommendation of London that
there "a man is always so near his ////now." 27

London was the principal center of science
in Britain for most of Lord Charles Cavendish's life
and for a good part of Henry's. Even though in the
second half of the eighteenth century, when much
of the important scientific activity took place
elsewhere, in the Scottish university towns and in
the industrial midlands, in the rising towns of
Birmingham, Manchester, and others, still London
remained "intellectually pre-eminent," a "magnet
for men with scientific and technical interests" and
the "Mecca of the provincial mathematical
practitioner."-'* Over half of the British scientific
practitioners of the eighteenth century who enter
the Dictionary of Scientific Biography worked mainly
in or near London.-' The city was large enough to
be home to numbers of experts in every part of
science, yet small enough for persons of common
interests to meet frequently in societies, coffee

houses, and priv ate homes. Scientifically interested
and interesting visitors from the provinces and
from abroad were warmly welcomed into these
circles. To paraphrase Johnson, as Lord Charles and
Henry Cavendish might have done: anyone who
was tired of London was tired of science.

Family of the Greys

After Lady Anne Cavendish's death. Lord
Charles kept in touch with the Greys, insuring that
although Henry Cavendish was brought up w ithout
a mother, he knew his maternal as well as paternal
family. We have Thomas Birch to thank for our
knowledge of Lord Charles Cavendish's visits with
his wife's family.

Birch owed his patronage to a branch of the
Greys, the Yorkes. Philip Yorke, first earl of
Hardwicke, engaged Birch as tutor to his oldest son,
who was also named Philip. He then kept Birch on,
from 1735, as a kind of secretary w ith light duties,
which left Birch plenty of time for his writing. 50

In 1740, the younger Philip married Jemima
Campbell, granddaughter of the duke of Kent.
That same year the duke died; thereupon Jemima
became Marchioness de Grey and Baroness Lucas
of Crudwell. In the years to come, in the off-season
Philip and Jemima lived at the duke of Kent's great
estate at Wrest Park in Bedfordshire, and the rest
of the time they lived in London at St. James
Square. No match for his self-made father the lord
chancellor, Philip rejected his ample opportunities
for high political office, withdrawing into his chief
pleasure in life, literature. In temperament he was
personable, languid and reserved, and in health he
was not robust. He spent much of the day dressing,
v isiting, and reading long letters from Birch. 51

27 Quoting an acquaintance on the importance of living in London:
James Boswell, The Life of Samuel Johnson I./..1)., vol. ■> (New York:
Heritage, 1%.?), 73. George Rude, Hanoverian London, 1714-1808
(Berkeley: University of California Press, 1971), 4-7. 25, ZH, 32-33.

2 *A. E. Musson and Eric Robinson. Science unit Technology in the
Industrial Revolution (Toronto: University of Toronto Press. 1969), 55,
57,66-67. 119. 138. E.G. R.Taylor, The Mathematical Practitioners of
Hanoverian England 1714-1840 (Cambridge: Cambridge University

Press. 1966). 14.

•'Dictionary of Scientific Biography , ed. C. C. Gillispie, 15 vols.
(New York: Charles Scribncrs Sons, 1970-78).

'"Albert E. Gunther, An Introduction to tin- Life of the Rev. Thomas Birch
D.D., F.R.S., 1705-1766. (Halesworth: Halesworth Press, 19H4). x, 35.

"Gunther, liirrh, 41. I,. H. and John Brooke, The House of
Commons 1754-1780, vol. 3: Members K-Y (London: Her Majesty's
Stationary Office, 1964). 681.

Copyrighted maier

Family and Friends

Birch was personally close to the younger
Philip Yorke, serving as his secretary, literary
assistant, and eyes and ears in London when Yorke
was at Wrest Park. Although Wrest Park appears
frequently at the head of Birch's letters, Birch's
principal assignment was London, from which
watch he kept his patron informed on literary
affairs and also on scientific affairs. Given Yorke 's
friends and membership in the Royal Society,
Birch expected him to take an interest in, for
instance, the test of John Harrison's chronometer
for determining longitude on a journey to Jamaica.
Philip Yorke's wife, Jemima, also took an interest in
science, for we find Birch writing to her about the
contents of the Philosophical Transactions? 2 When
Philip and Jemima Yorke were in London, Birch
would join them for weekly breakfasts at the Kent
family house on St. James Square." The duchess
of Kent was usually there along with Mary and
Sophia de Grey and other members of the Grey
family, including male in-laws Lords Glenorchy
and Ashburnham. Lord Gharles Cavendish visited
the Greys often in 1741 and 1742 and less often
over the next ten years, and sometimes he brought
along his son Henry to visit with his maternal
grandmother and aunts and uncles. u Henry
Cavendish may not have had a memory of his
mother who died when he was two, but his father
made certain that he knew the other dukedom from
which he descended.

Friends and Colleagues

Lord Charles Cavendish's friends and
colleagues tended to be one and the same. Apart
from those within his family, his friendships were
based not on aristocratic ties but on mutual
interests. His birth was no impediment to his
association with persons from other walks of life.

Many of Cavendish's friends belonged, as
he did, to the Royal Society Club. Originally
named the Club of the Royal Philosophers, its
members referred to it simply as "the Society." It
undoubtedly had a predecessor, but if Cavendish
had been a member then, it remains that he was
not elected to the Royal Society Club until eight
years after its founding in 1743. 35 From the
beginning of its records, the Club included close
friends of Cavendish, such as William Watson,
William Heberden, and Birch, and members of the
De Moivre circle, such as Folkes, Davall, Scott, and

Stanhope. The occasion of Cavendish's election
was the fatal illness of the president of the Club,
who was also the president of the Royal Society,
Folkes. This was at the end of 1751, when the
regular time for electing new members to the club
was many months off. As vice president. Cavendish
had already taken Folkes's place in the Royal
Society, and the Club wanted Cavendish to take
Folkes's place there too. Cavendish's election was
therefore made an exception, and in January 1752
he assumed the chair at the Royal Society Club.- 56

For convenience the Club met on the
afternoon of the same day the Royal Society met,
Thursday. Members of the Club did not also have
to be members of the Royal Society, but normally
they were, and the president of the Club was the
president of the Society. Its membership was fixed
at forty, though members could bring guests; when
Cavendish was admitted, the usual number of
members and guests was about twenty in the
winter and fourteen in the summer. The dinners,
which were heavy (fish, fowl, red meat, pudding,
pie, cheese, and alcohol), were held for the first
three years at Pontack's and then, throughout
Cavendish's membership, at the Mitre Tavern on
Meet Street. The ( Hub provided a fuller opportunity
than did the formal meetings of the Royal Society for
members to talk about science. Cavendish belonged
to the Club for twenty years and dined with it often,
but he did not attend the yearly business meetings
with any particular regularity, unlike Watson, Birch,

'- There arc many letters from Thomas Birth to Philip Yorke
reporting on scientific news between 1747 and 1762 in the Birch
correspondence in the British Library, Add Mss 35397 and 35399.
Thomas Birch to Jemima, Marchioness de Grey, 12 Aug. 1749, BL
Add Mss 35397, ff. 200-1.

"Gunther, Birch, 35-39.

,J We have no idea of the frequency of Lord ( Charles ( lavendish's
visits to his wife's family. Wc do know that he and Birch were at the
Grey's together twenty-six times between 1741 and 1751. On two of
the occasions Henry Cavendish came with Lord Gharles; Henry was
nine and ten at the time. Thomas Birch Diary, BL Add Mss 447KC.

• V, T. K. Allibone argues that the Royal Society Club was
continuous with "llalley's Club," for which he has a few pieces of
evidence. His assertion that Lord Gharles Cavendish was probably a
member of "llalley's Club" has none, however, so this lead we arc
unable to follow up. . . T. E. Allibone. The Royal Society and Its Dining
Clubs (Oxford: Pergamon Press. 1976). 45, 97. An opposing view of
llalley's part in the origins of the Club is given by Archibald Gcikic,
Annals of the Royal Society Club: The Record of a London Dining-Club in
the Eighteenth Nineteenth Centuries (London: Macmillan, 1917), 6-9.
Lord Charles Cavendish was elected to the Club on 25 July 1751 and
became a member on 9 January 1752.

3, "Allibone quotes from the Club's Minutes for 2S Nov 1751,
Royal Society and Its Dining Club, 44-45.

Cavendish

I Icbcrden, and several other friends, and for that
matter, unlike his son Henry later."

The Royal Society Club was the most
prestigious and probably the largest of the learned
clubs in eighteenth-century London, of which
there were many. Meeting to discuss science,
literature, politics, business, or whatever interests
drew men together, London clubs often had a
more or less formal membership, with rules and
dues, but often too they were informal; certain
persons simply formed the habit of being found at
particular hours at certain coffee-houses. Koikes,
president of the Royal Society, dined not only at
the Royal Society Club but as well at a club of his
own, which met at the Baptist Head in Chancery
Lane. Birch met with groups at Tom's ( Coffee
House and at Rawthmell's Coffee-House on
Henrietta Street, Covent Garden, later the place of
origin of the Society of Arts. Another society of
scientific and literary men met at Jack's Coffee
House on Dean Street, Soho, and later at Old (or
Young) Slaughter's Coffee House on St. Martin's
Lane, where De Moivre solved problems of games
of chance. 58 We do not know at which coffee
houses other than the Mitre Lord Charles
Cavendish might be found, but we do know some
of those where Henry Cavendish could be, a
subject we come to later.

Coffee houses and taverns provided clubs
with a measure of privacy in their supper rooms,
but these were noisy places at best. Private houses
provided quieter, more intimate settings for small
groups. Lord Willoughby, a prominent Fellow of
the Royal Society, presided both over a club that
met at a tavern — a life insurance society based on
the principles of the De Moivre student and
mathematician James Dodson, which met at the
White Lion Tavern — and over a club that met in
his and Birch's houses, alternately. 39 Another group
met at Macclesfield's. 40 Cavendish too dined with
his friends in houses, in particular, at his own house
on Great Marlborough Street. We have a record of
fifteen dinners he hosted between 1748 and 1761, to
w hich a total of thirty-two guests came, and to which
Charles's son Henry may be added. Birch was at all
of these dinners, necessarily, for our knowledge of
Cavendish's circle of friends comes from Birch,
who kept a social calendar in the form of a diary.

Cavendish's first mention in Birch's diary-
was in 1730, as if it were public news: "Ld Ch

Cavendish resigns." 41 The reference is clearly to
Cavendish's resignation as gentleman of the bed-
chamber to the prince of Wales. Birch's first
mention of any personal contact with Cavendish
was six years later, in 1736. Their connection then
was probably rather formal, since in that entry, and
in an entry a year later, Birch identified Cavendish
as the brother of the duke of Devonshire. 42 The
occasion for this early contact was Birch's scholarship,
for Birch recorded that Cavendish gave him original
papers concerning his grandfather William Russell,
who, Birch notes, was beheaded in Charles IPs
reign. 45 Here Charles was acting as a representative
of the great Cavendish family, but he and Birch did
become personal friends.

In August 1750 Cavendish invited Birch
and six other "Bretheren of the Royal Society" to a
"small Party," at which he offered a "philosophical
Entertainment of an artificial Frost by a Solution of
Sal Ammoniac in common Water," after which he
provided "what was equally relish'd, a very good
Dinner." 44 If Cavendish performed experiments at
his other dinners, we do not know, but it was not an
unheard of entertainment at the time. (This
particular experiment on artificial frost foreshadows
Henry Cavendish's later researches on freezing
solutions.) Earlier that same year, 1750, Cavendish
agreed to come to dinner at Martin Folkes's house,
to which John Canton was invited along with his

"Royal Society Club, Minute Books, in the Royal Society
Library. Cavendish resigned from the Club at the annual meeting in
1772, though he continued to take an interest in it, making it a gift of
venison five years later. Roval Society Club. Minute Hook, no. 7 (9
Sep. 1779).

"Thomas Birch, Oiary, BL Add Mss 4478C, 19 Oct. 1736. W.
Warburton to Thomas Birch, 27 May 1 738, in John Nichols,
Illustrations of the Literary History of the Eighteenth Century. 8 vols.
(London, 1817-58) 2:86-88, on 88. Bryant Lillywhite, London Coffee
Houses. A Reference Hook of Coffee Houses of the Seventeenth, Eighteenth,
and Nineteenth Centuries (London: George Allen and I'nvvin, 1963).
280-81, 369-70, 421-23, 595.

'''Lillywhite. London Coffee Houses. 745. Beginning in 1754, a
group met every Sunday at Willoughby 's house until spring, when it
moved to Birch's house; this alternation was kept up for years. The
regular members of this group were Watson, Hebcrden, Israel
Maudit, James Burrow. Daniel Wray, and several other Fellows of the
Royal Society whom Cavendish saw socially; he might be expected
to hav e belonged, but he did not. Birch Diary, passim.

«°Rodolph De Vall-Travers to Thomas Birch, n.d. /April 1757/,
BL Add Mss 4320. f.9.

41 Birch Diary. 12 Oct. 1730.

«Birch Diary, 29 June 1736 and 1 Aug. 1737.

«Birch Diary, 1 Aug. 1737.

♦•Thomas Birch to Philip Vorke, 18 Aug. 1750. BL Add Mss
35397. The guests were Birch, Folkes, I Icbcrden. Watson, Thomas
Wilbraham, and Nicholas Mann.

]hi«t material

Family and Friends

magnetic bars. Cavendish, Koikes told Canton, was
"very curious" to see Canton perform his magnetic
experiment, which Cavendish could do "more at
ease" at Folkes's house than he could at the Society.
The next year, when Folkes was ill, Cavendish
presided at the Royal Society and gave an
undoubtedly well-prepared, "excellent discourse" on
Canton's artificial magnets, for which Canton
received the Copley Medal. 45

Let us look at who came to dinner at
Cavendish's house. For example, on 21 October
1758 Cavendish had eight dinner guests, all
professional men out on the town, all but one
middle aged, some but not all married. They were
mutual friends, not people Cavendish brought
together for introductions. Besides Birch, two other
men at that dinner, Watson and Heberden, also
came to most of the other dinners at Cavendish's.
The guests were all Fellows of the Royal Society,
though with the exception of Birch, who was
secretary of the Society, they were not then on the
council. Cavendish, the only aristocrat, at fifty-four
was the next-to-oldest member of the party. Two
years older than Cavendish, Thomas Wilbraham
had long been practicing medicine in London and
was physician to Westminster Hospital. Birch was
fifty-three, like Cavendish a long-time widower,
with an adult daughter about thirty. Watson was
forty-two and married, or at least he had been
married, with a son about fourteen and a daughter.
Having started out as an apothecary, Watson now
had a mail-order doctorate from Cermany and was
practicing as a physician; in the minutes of the
meetings at the Royal Society, he had just begun to
be listed as "Dr. Watson." Heberden was forty-
seven, another widower, with a son about five who
was probably living at home. Farlier Heberden had
lectured on and practiced medicine in Cambridge,
but for the past ten years he had been practicing in
London. Israel Maudit was fifty, a rich bachelor,
who liked to entertain at home himself. Like a
good number of men who entered Cavendish's
scientific life — De Moivre, Desaguliers, Matthew
Maty — Maudit was of Huguenot descent and, it
stands to reason, a writer on religious freedom
(from having to subscribe to the Thirty-Nine
Articles of the Church of England, for example)
and politics. Samuel Squire was about forty-five,
married and probably with children by now (he had
three). Indebted to the duke of Newcastle for

advancement, this ambitious clergyman was about
to rise higher, to bishop. Gowin Knight was forty-
four and apparently unmarried. He was then
devoted to the mariner's compass and to his new
duties as principal librarian at the British Museum,
with a meager income of two hundred pounds a
year. The only young man in the company was
John Hadley, twenty-seven, who only that year had
been elected to the Royal Society. Hadley was still
trying to find his place in the world, dividing his
time between Cambridge, where he was professor
of chemistry, and London, where he was soon to
settle and become physician to St. Thomas's
Hospital. These were men of liberal outlook and
where their political leaning is known, whig. Some
of them were university men, some — including the
accomplished Birch and Watson, and the host,
Cavendish himself — were not. This dinner was not
a high-powered scientific gathering, though there
were some very good scientific men there. Only
the year before Cavendish had been awarded the
Copley Medal, as had earlier two of his guests,
Watson and Knight. Several of Cavendish's guests
were primarily interested in antiquities, which
made the party a mix like the Royal Society itself,
which was so obviously satisfying to Cavendish.
Only Watson had published extensively in the
Philosophical Transactions, on a variety of subjects,
including his professional field, medicine, but also
including electricity, on which he had important
papers. Knight too had published important
papers, his on magnetism, which just that year he
was bringing out in a collection. Heberden had
published four papers on miscellaneous topics, one,
a human calculus, falling within his professional
field, medicine. Birch too had published four papers,
one on Roman inscriptions belonging to his field,
history. Half of the guests were, like Cavendish
himself, one-paper men. Wilbraham had published
a medical account of an hydrophobia. Hadley's one
paper was yet to come, on a mummy examined in
London. Maudit's paper was on a wasp's nest.
Squire's was on a person who had been dumb for
four years and had recovered his tongue upon experi-
encing a bad dream. Since the dinner guests were all
men of learning, some, like Birch, had substantial
publications outside of the Philosophical Transactions.

«Royal Society. JB 20:571-73 (30 Nov. I 751).

Cavendish

Cavendish and Birch dined together at houses
other than Cavendish's in the period for which we
have a record, 1748 to 1762: at Heberden's and
Stanhope's houses as often as at Cavendish's, and
at Watson's, Macclesfield's, and Yorke's half as
often. Dinners at Macclesfield's were often
business meetings for the auditors too. Stanhope
we have met before as a pupil of De Moivre, who
had worked in the treasury and had served as a
Member of Parliament to 1741, the same year that
Cavendish had stepped down as Member of
Parliament; he was elected to the Royal Society in
1726, two years ahead of Cavendish. Stanhope
never married. Philip Vorke, now Viscount Royston
and about to become, in two years, the second earl
of Hardwicke, was a patron of Birch, as we have
seen, and an in-law of Cavendish; he held political
offices, and in 1741 he was elected a Fellow of the
Royal Society. 46 With Birch, together with other
men of science and learning, Cavendish dined two
hundred times, often at the Mitre with the Royal
Society Club. 47

Lord Charles Cavendish (and Henry
Cavendish) belonged to a circle that met in a
private house located in the Strand. Nothing is
known about it except that Cavendish's good friends
Ueberden, Watson, and Maudit also belonged,
along with several others. Most of the members
were physicians: in addition to I leberden and
Watson, they were George Baker, Richard Huck
Saunders, and John Pringle. Two others, John Ross
and Peter Holford, completed the circle, insofar its
membership is known. 4 " The interest that brought
these men together was probably science, though
in general outlook, there would seem to have been
a commonality too, which might be called a spirit
of enlightened protest. Upon becoming Bishop of
Exeter, the antiquarian John Ross advocated the
extension of toleration to dissenters in the House
of Lords. 4 '' We have already noted Maudit's
writings on religious freedom. John Pringle,
president of the Royal Society from 1772, made it
his lifework to reform medicine and sanitation in
the military. 5 " George Baker determined that in his
county, Devonshire, drinkers of cider were being
poisoned by lead; denounced as a faithless son,
Baker nevertheless got his fellow Devonians to
stop using lead vats, and he went on to clarify the
whole subject of lead poisoning. 51 Watson and
Huck Saunders were among the twenty-nine

"rebel Licentiates" who joined John Fothergill in
urging the Royal College of Physicians to admit
more readily as bellows physicians who did not
have an M.D. from Cambridge or Oxford. 52
Heberden, from within the College of Physicians,
sided with, and lost with, Fothergill, Watson, and
Huck Saunders. Heberden had already been a
thorn in the side of the College of Physicians with
his denunciation of mithridatum, a presumed
antidote to poisons, as an ineffective farrago; the
College nonetheless kept it in their pharmacopeia
until late in the century, until his former pupil
Cieorge Baker took over the presidency. Like
Birch, Heberden was a fervid whig, a Wilkite, and a
supporter of petitioning clergy. 55 Science, we see,
provided Cavendish not only an outlet for his
intellectual and administrative energies but also
provocative company committed to progress.

What brought Cavendish together with
Birch and the others was, apart from conviviality, a
common public world. Birch had recommended
several of Cavendish's dinner guests in 1758 for
membership in the Royal Society: Maudit,
Heberden, and Hadley. 54 Birch and Cavendish
worked together in the Royal Society year in and
year out. During the nine years centering on the
date of this sample dinner at the end if 1758,
Cavendish attended 81 meetings of the council of
the Royal Society, considerably more than did the
president, Macclesfield, with 63. Only two persons
came more times, necessarily, the secretaries:

**Birch's Diary records dinners in which Cavendish was present
at the homes of fourteen persons, all but one of whom were Fellows
of the Royal Society. The names are familiar: in addition to those
mentioned above, they include Josiah Colcbrookc, Samuel Squire,
Mark Akenside. Philip Vorke. Daniel Wray. and William Sotheby.

47 This count of two hundred is from Birch's Diary. It is a
minimum number, since Birch made his entries hastily, usually not
giving the names of everyone he dined with.

■•"Andrew Kippis's life of the author published in John Pringle,
Six Dist nurses, Delivered by Sir John Pringle, Hurt. When President of the
Royal Society; on Occasion of Six Annuel/ Assignments of Sir Godfrey
Copley's Medal. To Which Is Prefixed the Life of the Author, liy Andrew
Kippis, D.D. F.R.S. and S.A. (London, 1783), Ixiii-lxiv. Kippis says
that the group met at Mr. Watson's. This Watson he identifies as a
grocer, so he cannot be William Watson. Of the group, Peter Holford
is a relative unknown; he was elected Fellow of the Royal Society in
1747 and, much later, in 1783, a member of the Royal Society Club.

J ""Ross or Rosse, John." DNB 17: '66-67 .

^"Pringle, Sir John," D\'IS 16:386-89, on 388.

Sl "Baker, Sir George," DNB 1:927-29. on 928.

^Dorothea Waley Singer. "Sir John Pringle and His Circle —
Part I. Life." Annuls of Science t 1 1949): 127-80, on 161-62.

"Humphry Rolleston, "The Two Heberdens," Annals of Medical
History 5 < 19331:409-24, 566-83, on 412-13, 567-68.

M From Royal Society, Certificates.

Copyi^htrt maierial

Family and Friends

Davall 86 times and Birch, the record-holder, 96
times. Only one other Fellow came close, Burrow,
who was frequently a vice-president, with 76
attendances. 55 Little happened in the Royal Society
that Birch and Cavendish did not know about,
which was an important tie. Birch was an historian
who met the scientific and medical men more than
halfway. He was not a member of the College of
Physicians, but he was its chaplain, 56 and he
became a member of the Royal Society in 1735,
soon after embarking on his first great literary
work. When Pierre Bayle's biographical dictionary
was translated into English in 1710, London
publishers planned a patriotic revision that would
do more justice to English notables. Birch, at age
twenty-six, was invited to be one of the three
editors of the General Dictionary, Historical and
Critical , which appeared in ten volumes between
1734 and 1741, three volumes of which were
dedicated to presidents of the Royal Society.
Nearly all of the roughly nine hundred new lives
were written by Birch, who in writing about
English scientists such as Flamsteed and Newton
consulted the scientists who had known them,
Halley, Bradley, and Jones, who were the same
scientists from whom Cavendish also got his start.
Halley signed Birch's recommendation at the
Royal Society, which read that Birch was "well
versed in Mathematics and Natural Philosophy," 57
indicating that he was recognized for his scientific
knowledge as well as his literary attainments.
Birch's literary contributions to science continued,
his most important being his biography of the
seventeenth-century chemist Robert Boyle, to
whom he was drawn for his religious and scholarly
interests as well as for his scientific, a combination
of interests Birch himself had. Birch wrote enthusi-
astically of Boyle's mastery of Greek, which enabled
him to read the New Testament in the original, of
Hebrew, which led him to the Rabbinical writings,
of Chaldee and Syriac and Arabic, of the vast
collection of commentaries on controversies in reli-
gion, of the mathematical sciences, of geography,
history, medicine, natural history, natural philos-
ophy and, above all, chemistry. 58 Birch wrote of, or
implied, the importance for one's scholarly work of
living near other scholars, as Boyle did at Oxford,
and as Birch himself did in London, meeting with
them in its coffee houses, salons, and institutions of
learning. 5 '' In 1757, he completed a history of the

Royal Society. He had intended to bring it up to
date, to 1750, but in four volumes he did not get
past the seventeenth century', which is where he
left it. He wrote his history from the original
journals, registers, letters, and council minutes of
the Society, documents which he largely
reproduced; his method of history was the method
of science, as he understood it, the bringing
together of facts. "No fact has been omitted,"
Birch said, and he might have said that no analysis
was included: dense with footnotes, his history is a
chronicle of the Royal Society, meeting by
meeting/' 11 Birch, who depended on clerical living,
presented his sermons in the same spirit, citing
chapter and verse, Newton as well as the
Scriptures/' 1 An historian who wrote of science to
praise it, a man of learning, convivial and energetic,
Birch was a natural for scientific society.

Like Birch, Heberden was both an intimate
friend of Cavendish and a participant in Cavendish's
public world. Like Birch again, Heberden, a
physician, met the men of science more than
halfway; if Birch brought the method of science to
history, Heberden brought it to medicine.
Heberden's goal was to make the College of
Physicians a medical version of the Royal Society, a
proper scientific body. He used his influence in the
College — in which he took on the duties of
councillor, censor, and elect, one of the powerful
senior fellows who chose the president from among
themselves — to get it to establish a committee of
papers and a journal modeled and named after the
Royal Society's Philosophical 'transactions, the Medical
Transactions. Consistent with his belief that until "a
Newton appears in the science of the animated
world" to discover the "great principle of life,"
medicine had only one recourse, experience, he
regarded his job as the patient and laborious
assembling of facts. He was a painstakingly accurate
observer who made no large generalizations (or

"From Royal Society. Minutes of Counc il.

»C. Barton to Thomas Birch. 19 Sep. 1754, BL Add Mss 4300,
f. 1 74.

"Gunthcr. Hireli , 13-19.

•'"Thomas Birch, The Life of the Honourable Robert lioyle (London.
1744), 304-7.

''Birch, lioyle, 113- 14.

"Thomas Birch, Tit History of the Royal Society of London for
Improving, of Satural Knowledge, from Its hirst Rise . . ., vol. 1 (London,
1756), ([notation from the preface.

''' Quotations from Newton's Optieks in notes to his sermons:
Thomas Birch's Sermons, vol. 7, f. 188. BL Add Mss 4232C.

Cavendish

discoveries). Despite his admonitions to physicians
to publish, he himself was reluctant to do so. His
high reputation was based on his practice and his
knowledge of the classics, a combination in irre-
versible decline. Upon being asked what physician
he wanted in his final illness, Johnson called for
Meberden, "the last of our learned physicians." 62

Watson, a friend and colleague regularly to
be found in Cavendish's company, kept the Royal
Society abreast of the major developments in
science. For his role as informant, he was well
equipped, equally capable of giving the Society a
thorough exposure of Franklin's work in electricity
and Linnaeus's work in botany. More than any
other member, he made the meetings of the
Society scientifically rewarding. He also entered
energetically into the administration of the Royal
Society as he did into that of the other institutions
he served, which were more or less the same ones
that Birch, Heberden, and Cavendish served/''

In personality and appearance, Heberden,
Watson, Birch, and Cavendish were as different as
their public endeavors were similar. Heberden was
tall, extremely thin, short-sighted, with a florid
countenance. 64 Watson gave an impression of
solidity, with his massive face, arched eyebrows,
and large eyes; in conversation he was forceful,
exact (because of his remarkable memory, his
friends called him "the living lexicon of botany"),
and a good judge of mcn. w What people thought of
when they thought of Birch was not his ap-
pearance, which was unremarkable except perhaps
for an alertness of expression, but his conversation,
which was irrepressible, "brisk as a bee," according
to Johnson, a connoisseur of conversation/" 6 This
was the company Cavendish kept.

We learn more about Cavendish's friendships and
associations by looking at his activity in the Royal
Society. Like every member, he could vote on
everyone who was considered for admission,
though there is no record of how he voted. There
is, however, a record of which candidates he
recommended and of the members with whom he
signed recommendations.

Even before a candidate was proposed for
membership, he was usually canvassed by the
council. The candidate then had to be formally
recommended by three or more members, who
drew up a sheet with their signatures, the candi-

date's name, address, and profession, and a brief
description of his qualifications for membership.
This sheet would be dated and posted by one of
the secretaries in the meeting room for the period
of several ordinary meetings before the candidate
was put to the vote. An exception was made for
peers and their sons and various dignitaries, for
whom only one recommender was required. 67 To
further a candidate's chances, other members could
add their signatures to the sheet. Ten, not an
uncommon number, signed Henry Cavendish's
certificate in 1760. Occasionally, there was a
groundswell of enthusiasm for a candidate, as there-
was for Captain James Cook, whose certificate was
signed by twenty-six members. Certain members
were constantly putting up candidates, and on them
falls a good share of responsibility for the Society's
early accelerated growth. In the first forty years the
number of ordinary members tripled to three
hundred, and the number of foreign members grew
even faster, rising to almost half the number of
ordinary members/'* During the twenty-five years
that Lord Charles Cavendish recommended candi-
dates, the growth of the Society had slowed to one
or two a year. Cavendish's own contribution was
moderate: between 1734 and 1766, he recommended
twenty-seven candidates, fewer than one a year.

Birch signed recommendations with Caven-
dish more often than any other member, nineteen
times. Birch, it should be pointed out, recom-
mended a large number of candidates, a half dozen
a year. 64 Next came Folkes with ten recommenda-
tions in common with Cavendish, then Watson and
Wray each with nine. This agreement is probably
not surprising, since Birch, Watson, and Wray, as

"Humphry Rollcston, "The Two Heberdens," 414, 417. Audlcy
Cecil Buller, The Life and Works of Heberden (London, 1879), 16,
21-22. William Munck, The Roll of the Royal College of Physicians of
London, Comprising Hiographiral Sketches of All the Eminent Physicians
Who., Sum,- \n Recorded in thi Annals, 2d ed., -t vols. (London, 1878)
2:159-64. William Heberden, Commentaries on the History and Cure of
Diseases, 2d ed. (London, 1803), 483, and appendix, "A Sketch of a
Preface Designed for the Medical Transactions, 1767," 486-94.

""Watson. Sir William," DNB 20:956-58.

"Rolleston, "The Two 1 lebcrdens," 416.

'-"Watson," DM1 20:957.

""Birch," DNB 2:531.

"Royal Society, Minutes of Council 3:51, 77 (20 Aug. 1730).

"'Henry Lyons. The Royal Society 1600-1940: A History of Its
Administration under Its Charters (Cambridge: Cambridge University
Press, 1944), 125-26.

''''In 1748-60. Birch recommended seventy-six candidates Royal
Society. Certificates.

CopynghiCTt m aerial

Ft/ wily and Friends

we have seen, were good friends of Cavendish.
Then came Jones, of the De Moivre circle,
Cavendish's own recommender; then Burrow; then
Willoughby. There was only one person who
signed often with Cavendish with whom he does
not seem to have had outside connections, John
Machin, professor of astronomy at Gresham
College and secretary of the Royal Society; Machin
died in 1751, early in this account, and he was in
poor health in his last years, which may explain his
absence. It should be noted that Cavendish joined
Sloane in his early recommendations until Sloane
retired as president in 1741. Among Cavendish's
ninety-three co-signers, most of the other familiar
names appear too, though with less frequency:
Heberden, Bradley, Stanhope, De Moivre,
Macclesfield, Scott, Jurin, Davall, and Richard
Graham, to name several.

If we turn now from Cavendish's co-signers
to the candidates he recommended, we get another
indication of his associations. In 1753 the council
resolved that candidates were to be known
"personally" to their recommenders, a practice that
in the past had usually been followed though not
invariably. 70 We can be reasonably certain that
Cavendish was on a personal basis with most if not
all of the persons he recommended. Seventeen of
the certificates he signed said that the candidates
were proficient in the sciences (designated variously
as natural philosophy, experimental philosophy,
natural knowledge, natural history, philosophical
knowledge, philosophy, and different branches of
science); six certificates mentioned mathematics,
three useful learning, two mechanics, and another
two astronomy. Seven of the candidates were distin-
guished in literature or polite learning, though never
that alone. There were a few other accomplishments:
antiquities, architecture, medicine, anatomy, musical
theory, and (not very helpful) learning and
knowledge. Two candidates were professors at
Cambridge and Oxford, about whom nothing more
needed to be given than the names of their
professorships, which in their cases were astronomy
and experimental philosophy. For one other
candidate no explanation was given other than his
position, under-librarian at the British Museum, an
institution in which Cavendish was an officer.
Recommenders of foreign members of the Society
did not have to know the candidates personally but
they did have to know their work. Cavendish

recommended two French candidates, one an
astronomer, the other known as the author of a
commentary on Newton's Principia. It is clear that
the persons Cavendish helped gain entry into the
Royal Society favored the physical sciences and
mathematics, as might be expected, but they were
not narrowly identified with particular fields or, in
most cases, even with particular sciences. This
dimension of generality is to be expected, given
the composition of the Society. Every candidate
Cavendish recommended was elected, with the
exception of his first; in 1734 Cavendish joined
Sloane and John Stevens, one of the surgeons to
the prince of Wales, and two others in a recom-
mendation of John Wreden, another surgeon to the
prince of Wales. As a recent gentleman to the
bedchamber of the prince of Wales, ( lavendish
would have known these surgeons; and because of
the highly political nature of this prince of Wales,
politics as much as qualifications may have led to
the rejection of Cavendish's candidate. That, in
general, it helped a candidate for Cavendish to
recommend him there can be no doubt. When
Joseph Priestley, who unlike Cavendish had to make
his living, which he did in part by the sale of his
books, heard that membership in the Royal Society
would encourage sales of his history of electricity,
he discussed his prospects and strategy' with his
friend John Canton. Priestley expected that not only
Canton but Watson and Richard Price would support
his candidacy, and "If L. C. Cavendish could be
prevailed upon to join you," he told Canton, " I
should think the rest would be easy." (Canton, it
would seem, refused to approach Lord Charles
Cavendish on the technical ground that Priestley
was not a "personal acquaintance" of his.) 71

Sorrows and Riches

Frederick Cavendish — Fredy, his family
called him 7 ' — followed in his older brother Henry's
footsteps, at a two-year interval. He first went to
Hackney Academy and then as a fellow-commoner

™Royal Society. Minutes of Council 4:1 1K-19 (10 May 1753).

"Joseph Priestley to John Canton, 14 Feb. 1766, Canton Papers,
Royal Society, 2:5S. Priestley was elected that year without the help
of Cavendish; Benjamin Franklin joined the other three instead.
Joseph Priestley to Richard Price, 8 Mar. 1766, in A Scientific
Autobiography of Joseph Priestley (1738-1804), ed. R, K. Schofield
(Cambridge, Mass.: M.D.T. Press, 1966), 17-19, on 19.

'-Henry Cavendish referred to "Fredy V letters and expenses in
"Papers in Walnut Cabinet," Cavendish Mss, Misc.

Cavendish

to Peterhouse, Cambridge. In the year after Henry
Cavendish came down from Cambridge, and in
his next to final year at Cambridge, Frederiek
Cavendish had a bizarre aeeident, falling from an
upper window in one of the courts and striking his
head. There is no indication of what he was doing
in that window. Riotous behavior at Cambridge was
common enough, prompting Thomas Gray to
change his living quarters and affiliation, from
Peterhouse, Fredericks college, to Pembroke. Or
maybe Frederick was in his window trying
Franklin's experiment on lightning. Whatever the
cause, the fall was serious, leaving Frederick's life
in the balance for a time and his head with a deep
indentation as a reminder of it." The accident
happened in late July or early August 1754. By mid
August Frederick was "mending, but not out of
danger." 74 That summer Charles Cavendish had
been dining frequently with his scientific friends;
then for four and a half months he dropped out,
due in part to Frederick's condition. 75 In mid
October Thomas Birch wrote to Charles Cavendish
to say that his friends hoped that "Mr. Frederick
Cavendish's Recovery" would soon allow him to
join them "in town." 7 '' Frederick did not return to
the university, and although he gradually regained
his health, his brain was permanently impaired.

Of how Frederick occupied himself in the
years after his accident, there is no account.
However, thanks to the legal and financial ties that
bound in the eighteenth century, we have his
father's view of Frederick's mental "state." As we
have pointed out, as the younger son of the marriage,
Frederick's eventual prosperity was looked after by
his mother, who at her death in 1733 left him her
one quarter share of the duke of Kent's Steane
estate, which was sold and converted into stock.
Also through her, after the duke of Kent's death in
1740, Frederick received 12,000 pounds. Finally,
from the proceeds from the sale of the Putteridge
estate in 173K and its aftermath, Frederick received
another roughly 17,300 pounds. 77 While still a
minor, then, Frederick became independently
wealthy. Only he was not independent according to
the argument his father made to justify his
management of Frederick's wealth, which, as it
turned out, was legally questionable if otherwise
understandable. The Steane estate and, after its
sale, the equivalent in stocks were placed in the
hands of trustees. In 1772, the last surviving

trustee, Lord William Manners, died, and his son,
John, did not want the inherited trusteeship. This
meant that Lord Charles Cavendish had to choose
new trustees, who would have to be persuaded of
the legality of the way the trust had been used in
the past. Cavendish wrote up a case for this
practice and submitted it for a legal opinion, which
went against his wishes. He had been receiving
first the profits from the Steane estate and after its
sale the dividends from stock. His explanation was
that because of Frederick's accident, "it was
manifestly improper to pay the money to him"
during his minority and even after; Frederick was
then thirty-nine, and "even now," Cavendish said,
"it appears to be doubtful whether it is prudent to
do it." The earnings from the trust Cavendish had
spent on the "maintenance & education" of
Frederick, the "expense of which greatly exceeded
the income of the estate, except in some of the first
years of F's life." The legal opinion he solicited
was that the trustees had no power to permit him
to receive that money for the purpose he gave, for
it was a father's duty to support his child. In the
eyes of the law, then, — although it was not put this
way — Cavendish had been stealing from his
disabled son, and he and his heirs (who would be
Henry Cavendish) were accountable to Frederick
for the money taken from him. Despite this ruling,
the new trustees chosen by Cavendish, all members
of the family, agreed to let him continue to accept
all dividends and interest from the funds in their
name. Henry Cavendish as well as Lord Charles
was a party to the new but, in effect, old financial
arrangements for Frederick's support. Several lawyers
got involved, but in the documents we have seen,
there is no suggestion that Frederick himself was
unhappy with his father. What we have learned
from them is that in Lord Charles's judgment, his
son Frederick was incompetent. 78

"Lord Charles's Cavendish's legal ease involving his marriage
settlement and Frederick's expenses, 30 Apr. 1773. Devon. Coll.,
L/l 14/32. "Memoirs of the Late Frederick Cavendish. Esq.,"
Gentlemen 's Magazine 82 (1812): 289-9 1 . on 289.

74 Lord Harrington to the duke of Devonshire, 17 Aug. 1754
Devon. Coll.. no. 260.119.

"Lord Charles Cavendish hosted a dinner at his house on 17
July 1754: the next time he dined with this circle was at Stanhopes
house, on 2 December of that year. Birch Diary.

11 'Thomas Birch to Lord Charles Cavendish. 17 Oct. 1754. BL
Add Mss4444. f. 180.

"Devon. Coll., L/l 14/32.

7H "Copy Case Between l ather and Son with Mr. Perryn," 30
Apr. 1773. Lord Charles Cavendish to S. Sedclon. 27 and 29 July

Family and Friends

If Henry Cavendish's biographer Wilson
was accurately informed, Henry and Frederick made
a visit to Paris at some time or other, probably early,
before Henry was well known. Travel abroad after
leaving the university was the standard way for a
young man to complete his education, and it would
seem that Henry combined this course with an
effort to include Frederick in the world. This
possible journey by the two brothers is the occasion
of the earliest anecdote about Henry Cavendish. At
a hotel in Calais, the brothers passed a room in
which a corpse was laid out for burial; neither said
anything, but the next day on the road to Paris, this
conversation supposedly took place. " 'Fred. C,
loq. — Did you see the corpse?' Henry C, res. — I
did.' " 79 This (Pinteresque) fragment is one of
many anecdotes that are meant to show Henry's
taciturnity. Beyond that, the possible truth in it is
the reserve between the brothers, for which there
is other, better evidence. Frederick and Henry's
relationship was cordial but distant.

Frederick was in effective retirement.
Henry's mother, Lady Anne, had been dead for
many years, of course, and his grandparents,
Cavendishes and Greys alike, were all dead. Henry,
now of age and home from the university, would be
truly close only to his father. Henry had a good
many nominally close relatives. At the time he was
born, he had fourteen first cousins, to which seven
more were later added. At the time he came of age,
all but two of the twenty-one first cousins were still
living. He had contact with many or all of them, but
he does not seem to have been particularly close to
any of them. None of them, it might be noted, had
any accomplishment in science.* 40

Lord Charles was evidently close to his brother
Lord James, with whom he had traveled abroad as a
youth. James was the older of the two, but he
deferred to Charles in family affairs: he asked
Charles to dispose of his mother's estate and gave
him power of attorney in all matters of their joint
executorship. 81 James's military life took him away,
for example, to Ireland;* 2 later he was a Member of
Parliament for Malton. In 1741, at age thirty-eight
he died. 8 '

Lord Charles's only surviving brother,
William, may have had an interest in science and
was at least sympathetic to persons with a scientific-
interest. Belatedly, he was elected to the Royal

Society in 1747, and he subscribed to a number of
scientific books to which Charles also subscribed;
e.g., De Moivre's in 1730, Roger Long's in 1742,
and Colin Maclaurin's in 1748. 84 William, however,
cared much more about paintings than he did
about science. The brothers saw one another from
time to time, at Chatsworth usually. Charles kept
accounts with William, 85 and he served him as a
political go-between, 86 but they led very different
lives, due in part to temperament and in part to
their order of birth. William and Charles started out
the same way, as Members of Parliament, only
Charles left politics and William did not and
realistically could not. After his father's death in
1729, William, as third duke of Devonshire, sat in
the House of Lords, where he rarely spoke, and
when he did it was with such a soft voice that no
one could hear him. Not a leader of the party and
not a fighter, William accepted high office without
high ambition. Like his father, he was a friend of
Walpole and did well by the friendship. Walpole
made him lord privy seal, then lord lieutenant of
Ireland, a responsible, highly lucrative job because of
its immense patronage. Local government was the

1772. "Discharge from the Right Honourable Lord Charles
Cavendish to John Manners Esq' as to Trusts tor his Lordship and
the Honourable Henry Cavendish & Frederick Cavendish His
Sons." Devon. Coll., L/14/32. The new trustees were Philip Yorke,
earl of Hardwicke and Lord Charles's nephews Lords Frederick and
George Augustus Cavendish.

"George Wilson, The Life of the Hon' 1 ' Henry Cavendish (London,
1851), IS, 173. Wilson was told about Henry and Frederick's trip
abroad by his informant in London. Tomlinson, who was told it by an
unspecified Fellow of the Royal Society.

""Of the cousins alive when Henry Cavendish was born, two
died young: Rachel Morgan and Edward Morgan. Omitting their
titles, the others were Elizabeth Morgan. William Morgan, Carolina
Cavendish, William Cavendish, Kli/abcth Cavendish, Rachel
Cavendish, George Augustus Cavendish, Frederick Cavendish,
William Lowther, John Cavendish, Jemima Campbell, and John
Ashburnham. The cousins born after Henry were Henry Gregory,
David Gregory, George Gregory, Jemima Gregory, Amelia Kgcrton,
John William Kgcrton, and Francis Henry Kdgerton.

■'Lord James Cavendish to Lord Charles Cavendish. 25 Mar.
1727 and 23 Aug. 1732, Devon. Coll., no. 34/2.

"-J. Potter to the duke of Devonshire, 3 July 173'), Devon. Coll.,
no. 252.1.

"Gentleman's Magazine 11 ( 1 741 ): 609.

"-•Subscriber lists in Abraham De Moivre, Miscellanea analytics dt
seriebus el quadratures (London, 1730); Roger Long, Astronomy. In Five
Hooks, vol. 1 (Cambridge, 1742); Colin Maclaurin. An Account of Sir
Isaac Newton s Philosophical Discoveries (London. 1748).

""Charles Cavendish. "Account between my br. Devonshire &
me. June 18. 1733," Devon. Coll., 86/comp 1.

"'In a dispute over appointments between the duke of
Devonshire and the duke of Newcastle. Duke of Devonshire to
Harrington, 8 and 20 May, 15 and 24 June 1755. Devon. Coll., nos.
163.51. 163.52, 163.60. and 163.62.

Cavendish

basis of political power in the eighteenth century,
and the lord lieutenant of a county was the highest
local official, though the lord lieutenancy of Ireland
had a trace of derogation. In any event, William
carried out his job competently for seven years.
William did favors for Walpole in kind, helping to
keep him in office/ 7 William was a hard drinker, a
gambler, not overly smart, and distinctly lazy. He
was also cautious and duty-bound, family traits,
which could be regarded as strengths. Johnson,
who rarely saw anything he could admire in a whig,
saw in William a man who was "unconditional ... in
keeping his word," a man of honor. 88 The record we
have of Charles's relationship with his brother
W illiam has entirely to do with money. That was so
even during the second Jacobite rebellion of 1745
(the first had been thirty years before, in 1717),
when the pretender. Prince Charles Edward Stuart,
landed in Scotland from Prance with seven followers,
raised an army, and after initial military victory ad-
vanced south a good ways into England. (If by
discussing in detail the political career only of the
second duke of Devonshire, who died in 1729, we
have given the impression that after the second duke
the dynastic future of the kingdom had been settled
in the Revolution, we again correct it: until this
rebellion, the tories remained by and large Jacobites,
who schemed to restore the Stuart dynasty with
foreign intervention. 8 '') The rebels reached as far as
I )erby, from where they menaced ( ^hatsworth. By sub-
scription William raised a regiment in Derbyshire to
stop the invasion, marching here and there, and
generally keeping out of the way until danger was
past. In London, Charles was William's surrogate
banker and advisor on how to save William's medals
then at Chatsworth; unless the medals were "sent
out of the Kingdom" (which speaks of the peril of
the dynasty, as Lord Charles saw it), he did not
think they could be saved if the French landed,
since there would be a rising right there.'" 1 Nothing,
as it turned out, had to be done, as the prince was
forced to retreat, and the revolt ended in 1746.

William had great confidence in his youngest
brother. Two years after succeeding to the
dukedom, William made out his will, in which he
left to William Manners and others his horses but
named twenty-seven year-old Charles Cavendish
and his wife, Anne, and Robert Walpole trustees
for his children,'" of which he had seven. Of the

four sons, three entered politics, all staunch whigs
and allies of Fox, and one entered the military,
which by then was an uncommon career for a
Cavendish. The youngest son, Lord John, who was
Henry Cavendish's age and went through school
with Henry, held cabinet posts and of the sons was
by far the most determined in politics. But the
oldest son, William, was the most determined in
love, and in so being, he knitted the two greatest
aristocratic families in science, Robert Boyle's and
Henry Cavendish's. When he was twenty-eight,
William picked for his wife the sixteen-year-old
Charlotte Boyle, a distant relation of the seventeenth-
century chemist. From the point of view of the
Cavendish fortune, she was a prize, the sole heir of
the immensely rich Lord Burlington. (There is a
story that I lenry Cavendish was brought up in
Burlington House in Piccadilly, but it seems rather
improbable. 92 ) But the Burlington family was
talked about not because of its wealth but because
of its scandals, which decided William's mother,
herself a commoner before becoming duchess of
Devonshire, against the match. The duke sup-
ported his son, the marriage took place, the
duchess became unhinged, and the third duke's
marriage fell apart. The practical result of all this

"Plumb, Walpole 1:42-43, 235-36, and 2:280.
""Pearson, The Serpent ami the Slag, 89-91; quotation from
Johnson on 90.

"'Romncy Sedgwick, The House of Commons 1715—1754 (New-
York: Oxford University Press, 1970), 2:ix.

"William, Lord Harrington to Dr. Ncwcomc, 14 Dec. 1745; Lord
Charles Cavendish to the duke of Devonshire, undated, Devon.
Coll., nos. 260.58 and 21 1.3. John VVhitaker to Dickenson Knight,
undated /174.S/; R. Knight to Dickenson Knight, undated /Dec.
1745/; John Holland to Ralph Knight, undated /l 745/, in Great
Britain. I listorical Manuscripts Commission, Report on the Manusrripls
of Sir William Fitzherbert. Hurl., and Others (London: Her Majesty's
Stationary Office. 1895), I — f>.S. William, duke of Devonshire to
Robert Wilmot, 25 Oct. 1745. in Great Britain. Historical Manuscripts
( Commission, Report on the Liang Manuscripts Preserve// in the I 'niversily

of Edinburgh, vol. 2 (London: His Majesty's Stationary Office, 1925),
549. Richard Burden to /Viscount Irwin/, 7 Dec. 1745. Great Britain.
Historical Manuscripts Commission, Report on Manuscripts in Various
Collections. Vol. 8: The Manuscripts of the Hon. Frederick l.inel/ev Wood:
M. I.. S, Clemens. Esq.; Philip Unwin, Esq. (London: His Majesty's
Stationary Office. 1913), 158.

■"Duke of Devonshire, "My Will," 1 Oct. 1731. Devon. Coll.,
no. 165.95.

''-Royal Society, //;/■ Record of the Royal Society of London. 4th ed.
(London: Royal Society of London, 19401, 65. By the time the
Boyles and the Cavendishes became in-laws (for the second time)
and the Cavendishes thereby acquired Burlington House, Henry
Cavendish was about to begin his university studies. We have not
been able to follow up this suggestion that Henry Cavendish lived in
that house, but. of course, it could be true, since we know very little
about his early years.

Family and Friends

turmoil was that the already fabulous Cavendish
estate nearly doubled in value. 93 To Williams
sorrow, his wife did not live long enough to become
duchess, and he himself did not live many years
after becoming the fourth duke. Lord Charles
Cavendish was the responsible family intermediary
once again; he met several times with the third
duke's lawyer in connection with Harrington's
marriage to Charlotte Boyle.'' 4

The third duke of Devonshire died in 1755,
and for a time his will was lost; it was Lord Charles
who found it, on a sheet of letter paper, almost
worn out (and not showy, in keeping with
everything else about the plain third duke), which
clarified the disposition of property and enabled
life to go on. 95 The third duke's daughters made
notable marriages too. Rachel married Horace
Walpole's (the gossip Walpole's) cousin and name-
sake, which might have been the reason why
Horace Walpole eventually visited Chatsworth and
changed his mind; before seeing the estate, he had
always run it down, but no longer. 96 Another
daughter of the third duke, Lady Carolina, married
William Ponsonby, second earl of Bessborough,
who at the time was secretary to the third duke as
lord lieutenant of Ireland. To their son, the third
earl of Bessborough, Henry Cavendish would leave
a sixth of his great fortune in his will. 97 The third
duke's third daughter. Lady Elizabeth, married
into the same family, John Ponsonby, and to make
up her dowry the duke borrowed from Lord
Charles Cavendish. The duke was rich in property
but, typically, short of cash. 98

For the women in his family, Lord Charles
Cavendish assumed various obligations. When he
was in his mid thirties, he together with his uncle
Lord James served as executors of the estate of his
aunt Lady Elizabeth (Cavendish) Wentworth. 99
Property was commonly assigned for raising
dowries, and in 1723, just after his daughter Diana
died in childhood, the second duke of Devonshire
set aside lands to raise 6,000 pounds for each of his
three surviving daughters. Ladies Rachel,
Elizabeth, and Anne. Rachel and Elizabeth were
about to be married at the time, and their brother
Charles was named representative for Anne, who
was without prospect and, in the event, never did
marry. In time everyone was paid off in cash with
interest to keep the properties within the
Cavendish estate, 100 but Charles had to talk hard to

bring Anne around to the logic of the family's
investments, she being "extreamly jealous, &
fearful of being injured." 101 Like all of the second
duke's daughters who did not die prematurely,
Anne lived a long life, dying in 1780 at age seventy.
Rachel, who married Sir William Morgan of Tredegar
of a family of big landowners and country whigs,
had four children, and lived upwards of eighty. 10 -'
Charles kept in touch with Rachel's family: when
her daughter Elizabeth married William Jones of
Llanarthy in 1767, Lord Charles was a party to the
settlement. 103 In 1723 Charles's sister Elizabeth
married the Member of Parliament for Lancaster Sir
Thomas Lowther, whose family together with the
Musgraves "controlled the nerve centre of political

'"Pearson, The Serpen! and the Stag, 93-KB.

' M Lord Charles Cavendish's involvement is reflected in the
statement of expenses rendered to the third duke by Hutton
Perkins, the duke's lawyer, on 13 May 1748. Devon. Coll.. no. 313.1.

1,5 R. Landaff to the fourth duke of Devonshire. 6 Dec. 1755;
Thomas Hcaton to the fourth duke of Devonshire, 6 Dec. 1755.
Devon. Coll., nos. 356.5 and 432.0. Thcophilus Lindsey to Karl of
Huntington, 24 Dec. 1755. Creat Britain, Historical Manuscripts
Commission. Report on l/ie Manust ripts of the Lute Reginald Raiadon
Hastings, Esq., of the Manor House Ashhy tie la Y.ourhe, 4 vols. (London:
His Majesty's Stationary Office, 1928-47)3:111-14. on 1 13.

'"•Pearson, The Serpent and the Stag, 102-3.

''"Entries for the second and third carls of Bessborough, in
Col/ins's I'eerage of England 7:266-67. Francis Bickley. The Cavendish
Family (London: Constable. 191 1 ), 207.

" The third duke of Devonshire created a bond to Lord Charles
Cavendish for 12,000 pounds, the purpose of which was to give the
duke power to raise 6.000 pounds for the down of Lady Elizabeth.
Lord Charles advanced the 6.000 pounds for this use. and the duke
agreed to take out a mortgage on his properties to repay Lord
Charles with interest. "Bond from His Cirace the Duke of
Devonshire to the Rt Honble Lord Charles Cavendish," 22 Sep.
1743. Devon. Coll., L/44/12.

"'"Probate of the Will of 1/ Eli/.. Wentworth 1741." Devon.
Coll., L/43/13. Lady Elizabeth was the widow of Sir John Wentworth
of Northempsall. Seven years later. Lords Charles and James
Cavendish were released from any further claim on them as executors
by another Lady Wentworth, Dame Bridget of York: "1/ Wcntworths
Release to Lady Betty VVentworths Executors March 5 1748." But
Lord Charles kept a notebook for Lady Betty Wentworth *s personal
estate for twenty years, from 1741 to 1761. After 1748 Lords Charles
and James received a small dividend from two hundred shares of
South Sea stock regularly. After Lord James's death, his part went to
Richard (Chandler) Cavendish and, eventually, to Lord Charles.

""'"Deed to Exonerate the Estate of the Duke of Devonshire
from the Several Portions of Six Thousand Pounds ... to be Directed
to Be Raised for Lady Rachel Morgan, Lady Elizabeth Lowther and
Anne Cavendish the Three Surviving Daughters of William Second
Duke of Devonshire ... ." 28 July 1775. Devon. Coll., L/19/67.

'•'Lord Charles Cavendish to Hcaton, 18 Aug. 1775, draft, and
"Account of Deeds to Be Executed by Lord Charles Cavendish."
Devon. Coll.. 86/comp. 1.

m Collins's Peerage of England 1:356. Holmes, British Politics . . .
Anne, III.

""Articles on the marriage of William Jones and Miss Morgan,
daughter of Ladv Rachel Morgan, to which Lord Charles Cavendish
is a party, 4 July 1767: Devon. Coll.. L/43/16.

Cavendish

power in the two border counties of Cumberland
and Westmorland." 104 The Lowther connection
drew Charles into a legal fog worthy of Dickens.

Frequently Lord Charles saw his sister
Lady Elizabeth at Chatsworth or at Holker, the
great Lowther house in Lancashire, edged with
magnificent gardens, set on a wooded, hill v park on
M orecambe Bav. " b Charles was named godfather
to Elizabeth's second child. 10 ' 1 Then the troubles
began. The spunky Elizabeth, w ho wished she had
been a brother so she could have gone abroad with
Charles and James, went insane. In 1737 she was
placed in the hands of physicians "to try what
effect it will have upon her to make her of better
behaviour." 107 (It evidently had none; it may be
that she was placed in Saint Lukes Hospital for
Lunaticks, since Sir James Lowther left a bequest
to it in his will. 108 ) Sir Thomas, her husband, a kind
but improv ident man, lapsed into heavy drinking
and debt. In 1745 Thomas died at Holker without
a will, and his and Elizabeth's one surviving child,
William, was placed under the guardianship of
Lord Charles Cavendish, the duke of Devonshire,
and Lord Lonsdale. 10 '' Charles pursued every
possibility of turning the encumbered Lowther
property into cash; e.g., Thomas had been a hunter
and had dogs, w hich Charles wanted to sell, as he
explained to the agent on the scene: "people arc-
more inclineable to beg than to buy, but my
business is to sell & not to give." Charles wanted
to sell the beer too, since it would not be "worth
the Guardians while" to buy it for Sir Williams use
when he came of age.' 10 Soon after Thomas had
died, another Lowther died, his cousin John, leaving
most of his estate to Thomas and Elizabeth's single
child, William, and Charles had now to sort out the
details of this property as well. Charles made notes
of 120 letters in one of the books he kept on the
Lowther business. Young William Lowther, in the
meantime, was now at Cambridge desiring books
from his father's library and money for his tutor and
tailor, and contemplating a political life. Debters
were on Charles's back. For Elizabeth, "Lady B."
(Lady Betty), his insane sister and now widow, he-
paid a fee to the best doctors in London, Drs.
Richard Mead and Edward Wilmot, another to her
apothecary, and still other bills to other persons.
She did not live long after he took charge of the
estate." 1 Charles kept on friendly terms with
William, his former ward, now of age, inviting him

to dinner at his house with scientific friends in
1753."- That year William was appointed lord
lieutenant of Westmorland," ' and two years later
he was elected a Member of Parliament. Then sud-
denly, in 17.56, while attended by Drs. Heberden
and Shaw, Sir William died of scarlet fever. Sir
William in the meantime had acquired immense-
riches from his distant uncle Sir James Lowther of
Whitehav en, who died in 1755." 4 This Lowther was
the fourth mainly rich Lowther to die in just over
ten years. There was a funneling effect, with the wealth
piling up. Sir William brought a fortune close to the
bosom of the Cavendishes, which was seen as a
kind of family coup. 115 He was only twenty-eight
when he died, and he had no son to succeed him.
His will directed his estate to go to certain people
and the work of distributing it to Lord Charles
Cav endish, who was entitled to residual plunder." 6
According to an acquaintance of Henry
Cavendish, the Lowther estate at Holker was
owned by Lord Charles Cavendish and then by

t0 *TAe I. tuition Diaries of W illiam Nicolson Hishop of Carlisle 1701-
1718, ed. C. Jones and G. Holmes (Oxford: Clarendon Press, 1985), 3.

l05 Sir Thomas Lowther to Sir James Lowther, 12 Aug. and 5
Sep. 172o, and 11 July 1734. Cumbria County Record Office,
Carlisle, D/Lons./W. Bundles 30 and 37. The Victoria History of the
County of Lancaster, ed. W. Farcr and J. Brownbill, vol. 8 (London:
Constable, 1914). 270-72.

""' Thomas Lowther to James Lowther, 8 Aug. 1728, Cumbria
County Record Office, Carlisle. D/Lons/W, Letters. 39: Misc.
Letters & Papers. 1728-39.

l07 Sir James Low ther to John Spedding, 16 June 1737; quoted in
J. V. Beckett, " The Lowthers at Holker: Marriage. Inheritance and
Debt in the Fortunes of an Eighteenth-Century Landowning
Family," Transactions of the Historic Society of Lancashire and Cheshire
127(1977): 47-64, on 51.

'""Sir James Lowther's will. 1754. Devon. Coll.. L/31/17.

""Court appointment of Lord Charles Cavendish as
administrator of Sir Thomas Lowther's estate: Devon Coll.. L/l 1/31.
Lord Charles Cavendish to John Fletcher, 18 July 1745; Kdward
Butler to John Fletcher, 16 May 1745. Lancashire Record Office.
DDca 22/5 and 22/3/1.

""Lord Charles Cavendish to John Fletcher, 27 July 1745; Lord
Charles Cavendish to William Richardson. 29 .Mar. /1 746/.
Lancashire Record Office. DDca 22/5 and 22/7.

"'Lord Charles Cavendish, third notebook, in Devon. Coll.,
L/43/14. Elizabeth Lowther died in 1747. according to Beckett,
" The Low thers at Holker," 51.

l,2 Birch Diary (5 June 1755).

" 'Beckett. "'The Lowthers at Holker," 51.

ll4 Sir James Lowther's will of 1754. Devon Coll.. L/31/17.

" s Henry Fox wrote to Hartington, who in two months would
become the fourth duke of Devonshire. "I must wish y Lordship Joy of
the very great Acquisition made by your near Relation Sr. W. Lowther,
w hich I am credibly informed, is 4.000 pounds a year in Land. ( loal Mines
bringing in 1 1,000 pounds a year. & not less than 400.000 pounds in
Money. Sr. James Lowther has 100,000 pounds & an Kstate in Middlesex,
not a great one." Letter of 4 Jan. 1 755. Devon. Coll., no. 330.30.

"'•What was not specified in the will went to Lord Charles
Cavendish, the sole executor. "Inv entory of W rought Plate from

Copyi*]hi«t maieri

Family and Friends

Henry, but this account puzzles us and can hardly
be right. Holker and another nearby estate,
Furness, were devised by Sir William to his
maternal cousins Lords George Augustus and
Frederick Cavendish, sons of the third duke of
Devonshire. 117 This is not to say that Lord
Charles would not have liked to own the valuable
and beautiful estate of Holker.

The great portion of the wealth of the
deceased Sir William was reverted by the will of
the deceased Sir James Lowther to another James
Lowther, the future first earl of Lonsdale, who was
not yet of age. The sudden fortune of this young
man prompted Horace Walpole to fear that
Fngland was becoming the "property of six or
seven people." 118 Cavendish, as Sir William's
executor, was soon in conflict with young James
Lowther. His overseeing of the Lowther
properties — manors, farms, collieries, iron pits, lead
mines, fire engines, timber, even a fishery — was an
immense job, which now became compounded by
a law suit. Katherine Lowther, James's mother,
thought that Cavendish was unreasonable and
hard. She had a point, though both parties appear
grasping. It is clear that Cavendish hoped to profit
from a technicality arising from the close deaths of
Sir James and Sir William Lowther. Cavendish was
not only William's sole executor, he was also sole
executor of James, since the original executor,
William, had died almost immediately after James.
Charles claimed that Sir James's residual estate,
consisting of collieries, land, and buildings, passed
through Sir William to him. He also claimed 30,000
pounds in New South Sea Annuities, which were
put in trust to finance the transfer of Sir William's
estate to young James. Charles argued that these
funds were his because the transfer of estates could
not take place in the specified time for the reason
that James was not of age." y Charles, that is,
claimed property that fell through the legal net; for
in neither will was he the intended beneficiary.
The case was debated, council on both sides was
heard, and the judge declared that the collieries
and so forth belonged to young James and that the
30,000 pounds did too and that Cavendish was to
pay over to young James the interest on those
annuities. Charles lost completely. 120 As the
biographers of Lord Charles Cavendish, we are
partial and take satisfaction in what young James
Lowther, earl of Lonsdale, made of his great

wealth. He proved to be a successful politician,
who insured his own elections and commanded
those in several other seats by means of lavish
expenditure. He owned nine Members of
Parliament, who were called "Sir James's Ninepins."
In part because of the way he used his wealth to
exercise power and in part because of his character,
he was known in his counties as the "bad earl." In
boasting that he owned the land, fire, and water of
Whitehaven, he was referring to the collieries and so
on that came to him from Sir James Lowther's estate
instead of going to Lord ('hades Cavendish. 121

The Lowther affair occupied as many pages
of notation and probably as much time as Lord
Charles Cavendish's scientific experiments.
Throughout, Cavendish exercised the hereditary
instinct of his family to acquire property. The

I lolker" is u long list of flatware ami hollow w are. The numbers along-
side the items are in Henry Cavendish's hand. Devon. Coll., 86/eomp. 1 .

"'John Burrow, who knew Henry Cavendish from the Royal
Society Club, recalled that Cavendish told him that Lord George
Cavendish left Holker Hall to his father and that his father left it to
him. Cavendish told him that he wanted to do with this what the
iron-founder John Wilkinson had done with his property across the
bay from I lolker. expand it into the water. John Barrow. Sketches of the
Royal Society and Royal Society Club (London, 1849), 146-47. But that
Lord George (Augustus) died in 1794, after Lord Charles. In the year
Sir William Lowther died. Lord Charles Cavendish learned that
Katherine Lowther (see below) had "thoughts of making over the
estate /of Holker/ to Lord George for a consideration." Charles
Cavendish to William Richardson, 28 Dec. 17.S6, Lancashire Record
Office, DDca, 22/7. Lord George (Augustus) Cavendish acquired
Holker and went there frequently, and as late as around 178H he was
making alterations in the gardens. Victoria History of the County of
Lancaster, 271. Holker eventually went to Henry Cavendish's heir
Lord George (Augustus Henry) Cavendish, but not through Henry
Cavendish. A confusion may have arisen from the rectory of Cartnicl,
near Holker, which Lord Charles Cavendish and after him Henry
held in trust. There is a long series of leases in the Cavendish estate
papers, beginning with "Copy of the Lease of the Rectory & Tythcs
of Cartmell from the Bishop of Chester to Lord Charles Cavendish
for the Lives of Sir James Lowther. Mrs. Katherine Low ther & Lord
George Augustus Cavendish." Devon. Coll., L/36/62. The trust took
over the payments that the Lowthers earlier had paid directly to the
bishop of Chester for the rectory of Cartmel. Beckett, " The
Lowthers at Holker," 54.

' "Horace Walpole to Montague, 20 Apr. 1756, Horace Walpole's
Correspondence, ed. VV. S. Lewis, vol. 9 (New Haven: Yale I niversitv
Press. 1941), 183-87. on 18.5.

"''Katherine Lowther to James Lowther, 8, 11, 15, 19 July 1756;
"Heads of What Is Agreed on between L d Charles Cavendish & Sir
James Lowther." n.d. Cumbria Record Office, Carlisle, Archive,
D/Lons/Ll/61 and 62.

'-""Sr. W. & Sr. J. Lowthers' Wills & Papers Relating to Law
Suit between L.C.C. & Sr. J. Lowther." Devon. Coll.. no. 31/17.
Cavendish appealed the decision concerning the 30,000 pounds.

'•^"Lowther, James, Karl of Lonsdale," DNB 12:217-20. We
have referred only to Low ther's flaws. He w as capable of exercising
good political judgment: during the American Revolution, for
example, he was active on the side of Lord John Cavendish and the
other whigs who opposed the war and George III.

Cavendish

dispute was entirely impersonal on Cavendish's
part, and precisely for that reason, it gives us an
insight into his person. His involvement came
about because of his mad sister, who had married a
Lowther, but it became more than a family duty; it
became an unexpected opportunity. Without
question, at a certain point Cavendish thought that
he was going to become a very rich man into the
bargain. I le was aware that he was in a delicate
position, since any worldly goods that came to him
did not go to another, the last in this sequence of
Lowthers, the still-living (and still minor) James.
The Lowther riches were intended to go to a
Lowther, as was right and proper. Lord Charles
Cavendish had been invited in as an administrator,
but because he was also something of an interloper
too, he took pains to make clear that his claim on
William's personal estate did not arise out of greed:
"I do not desire to have a farthing more than I have
a right to." We have to take this man of principle at
his word: what was his was his by right, and so by
"law as well as from the principles of justice," he
was "intitled" to a full disclosure of the extent and
value of the estate. In this matter he believed he
had not been treated with "strict justice." For his
part in this dispute over interests, he intended to
"act with perfect openness & candour."'" The ex-
pressions that Lord Charles Cavendish used, "strict
justice" and "perfect openness," are those, as we will
see, that his son Henry would use. They applied
equally to personal conduct, politics, and science.

Try as hard as he might. Lord Charles did not
grow rich through the Lowthers. He did become
rich, but it was to be from another line of the
family. Elizabeth Cavendish, another Elizabeth —
Elizabeth was one of the often repeated Cavendish
names, starting with the impressive founder of the
family's riches, Bess of Hardwick — was a younger
first cousin of Charles. Her father was Lord James
Cavendish (Lord Charles's uncle, not his brother of
the same name), a Fellow of the Royal Society,
who had an interest in mathematics and natural
philosophy, 123 and her mother was Anne Yale,
daughter of Klihu, a rich diamond merchant and
governor of Fort St. Ceorge in Madras, after whom
an Ivy League university is named. In 1732
Flizabeth married the politician Richard Chandler,
son of Edward Chandler, bishop of Durham, just a
year after Lord James's other child, William, had
married another Chandler, Barbara. Richard

Chandler was a man of wide learning, with a very
substantial library; he and Lord Charles Cavendish
would seem to have had interests in common. 124 In
1751 Elizabeth's father and brother both died, and
her mother had died earlier, leaving only her and
Richard Chandler to continue that branch of the
family. That year, 1751, Richard took his wife's
name and was known from then on as Richard
Cavendish. Richard Cavendish died before
Elizabeth, leaving her sole owner of a house in
Piccadilly, and a great deal more real estate and, in
addition, a large sum in securities and mortgages. 125
Having no children, she originally intended to
leave her real property to the duke of Devonshire
and the rest of her estate to her only living male
first cousin on the Cavendish side, Charles. Shortly
before her own death, however, she changed her
will, cutting off the duke (her second cousin) and
naming as co-executor with Lord Charles Cavendish
the prominent lawyer and politician Lord Charles
Camden. The two executors were to hold the
Piccadilly house in trust, but otherwise, as far as
Cavendish was concerned, the will was practically
the same. Cavendish took upon himself the task of
executing the will, which, except for the land and
specific requests, left everything to him. 126

To begin with relative trifles: as residuary
legatee, Lord Charles Cavendish was entitled to
Lady Elizabeth's diamond earrings, pearls, soli-
taire, coins, Oriental stories, and so on, but in so
avaricious a family as the Cavendishes, his right to
these things did not go unchallenged. This time
Charles prevailed. 127 The main point was the

l22 Lord Charles Cavendish to William Richardson, 2d and 29 June
and 27 July 1756. Lancashire County Record Office, DDca, 22/7.

'-'Lord James Cavendish and Lord Charles Cavendish together
recommended Gowin Knight for fellowship in the Royal Society for
his "mathematical and Philosophical knowledge," 24 Jan. 1745,
Royal Society, Certificates, vol. 1, no. 14, f. 297.

124 Richard Chandler's library was evidently on all subjects,
including science; it contained books by Newton, Bovle, Hooke. and
a good many eighteenth-century scientific writers. A Catalogue of a
Large, Valuable, ana' Elegant Colla tion of Hooks; Including the Libraries of
the Late Richard Cavendish, Esq.; the Rex.-. Dr. Jortin. and Several Other
Curious Panels Lately Purchased . . . The Sale Will llegin in February
177/ .. . By Benjamin White, at Horaces Head, in Fleet .Street, London.

12S The round figure of 30,000 pounds turned up again, this time
in a promise by the duke of Devonshire to repay that amount to
Lady Elizabeth. The duke's promise is in a formal letter enclosed in
the document, "The Duke of Devonshire to Lord Charles
Cavendish and Mr. /Dudlev/ Long, Lease for a Year, 15 June 1772."
Devon. Coll., L/19/64.

'-'■Lady Elizabeth Cavendish's will, 26 Feb. 1778. Devon. Coll.,
L/31/37. In a codicil of 31 Jan. 1779, she removed her real property
from the duke of Devonshire, substituting Dudley Long.

IM material

Family and Friends

wealth on paper: 75,000 pounds in three pereent
consolidated bank annuities (consols), 22,000 pounds
in three percent reduced bank annuities, and
47,000 pounds in mortgages. Elizabeth Cavendish's
will was brought to court in May 1780, and three
and a half years later the fortune it had bequeathed
to Charles Cavendish became the property of his
son Henry. 128

'""Copy Case with Mr. Att> General's Opinion." 1780. Devon.
Coll., L/l 14//74. The judge, in coming down on Lord Charles's side,
declared that the jewels were personal ornaments, not part of a
"collection" to be preserved for posterity. This was not the end of
the matter: "Lord Geo. Cavendish & Lord Camden Bill," 1782, ibid.

,2 ""Lord Camden and the Honourable Henry Cavendish
Assignment and Deed of Indemnity." 31 Dec. 1783, Devon. Coll..
L/31/37. Also "Copv of Mr Pickerings Letter to Mr Wilmot." Zh Apr.
1780, ibid., 86/comp. I.

Copy lighted maw

CHAPTER 4

Public Activities

Public Life

Lord (Charles Cavendish was a man of reason,
whose manifest administrative skills were valued
in arenas outside of politics and science, in the
founding and working of new institutions. The
people he worked with were, in many cases, the
same people he worked with in politics and science.

For twenty years Robert Walpole kept the
country in peace and prosperity, during which time
London acquired several new institutions. They
included hospitals, Westminster in 1720, Guy's in
1724, and several more by 1740. These were
hospitals in the usual sense of the word, and in
addition there was a new charitable hospice for
unwanted children, the Foundling Hospital.
Inspired by foundations for this purpose on the
Continent, in Amsterdam, I'aris, and elsewhere,
the Foundling Hospital was the culmination of an
arduous and heartfelt campaign by Thomas Coram
on behalf of "great numbers of Helpless Infants
daily exposed to Destruction," as he put it in a
memorial addressed to the king. The Hospital was
incorporated by royal charter in 1739, in a
ceremony attended by bankers and merchants
from the city and by six dukes, eleven earls, and
assorted lesser peers, who set the tone of the
endeavor. The charter was received by the
president of the Foundling Hospital, the duke of
Bedford, a relative of Cavendish. Cavendish's
brother the duke of Devonshire and his father-in-
law the duke of Kent were named in the charter as
original governors. Lord Charles Cavendish
himself was elected governor later that year. 1 The
Foundling Hospital was first located in a leased
house, but soon, by 1752, it had acquired a new
building, set in the fields, like the buildings of
most other new institutions in eighteenth-century
London. This building, a pair of Georgian brick
blocks flanking a deeply recessed entrance, was in
its way an imposing structure, almost palatial.
Because the Foundling Hospital was financed by

private wealth, with some help from parliament, its
new building was architecturally elaborated,
unlike, say, the new London hospitals, which were
financed by annual subscription. The interior of
the Hospital was adorned with paintings; elegant
concerts were held there. 2

This fashionable charity needed adminis-
trators who were both able and hardened to the
task, for conditions of life in an eighteenth-century
foundling hospital were, at best, appalling. During
the first four years, the Hospital admitted children
indiscriminately, whether true foundlings — exposed
and deserted children who would otherwise die —
or not, nearly a hundred a week at times. Of the
roughly 15,000 children received then, over 10,000
did die, a mortality rate of seventy percent. An
unanticipated traffic sprang up. Infants from the
provinces were brought to London under barbaric-
conditions and dumped at the Hospital, thereby
sparing parish officials the trouble and expense of
maintenance. Parents exploited the Hospital too by
abandoning their children there, more dead than
alive, to avoid the cost of burial. The administrators
of the Hospital had to deal with the consequences
of and, ultimately, with their policy.

Public attitude favored the Hospital. There
were practical as well as humanitarian reasons why
children should be saved if possible; e.g., to keep
the kingdom from running out of soldiers after the
high casualties in the recent war with France. The
best medical opinion in London was made avail-
able to the institution. Hans Sloane, president of
the Royal Society, and Richard Mead, both of
whom were named in the charter, were among the
leading physicians who volunteered their expensive
services. Cavendish's good friend and colleague at
the Royal Society William Watson, an expert on

1 R. H. Nichols and F. A. VVray. The History of the Fount/ling
Hospital (London: Oxford University Press, 1935). 16, 19.

-John Summerson, Georgian London, rev. ed. (Harmondsworth:
Penguin Books. 197H), 119-20.

<V(5

infectious childhood diseases, was appointed
physician to the Foundling Hospital. Watson
distinguished himself in the crusade of the
I lospital to prev ent the devastations of smallpox,
which was then a disease that primarily struck
children under three. 3

At about the same time that Cavendish was
elected governor, the next two presidents of the
Royal Society, Folkes and Macclesfield, were
elected governors too, and all three went on to
become vice-presidents of the Hospital. The job of
vice-president was not a ceremonial but a working
job, the only kind Cavendish ever took on. 4
Cavendish spent endless hours at the Hospital
every week, over decades.

With the desire to put its children to work, the
Foundling Hospital turned for help to the white-
herring industry. The Society of Free British
Fisheries, having encouraged the setting up of the
famous Ropeyard in the Colonnade, in 1753 agreed
to buy as much Yarmouth Shale as the foundlings
could braid. It turned out to be considerable; a work-
shop for the purpose was laid out in a converted
kitchen in the Hospital and was proudly opened to
the public so that it could observe the children at
work. s Lord Charles Cavendish was active at both
ends of this arrangement; he was not only a governor
of the Foundling 1 lospital but also a member of the
council of the Society of Free British Fisheries. 6

Incorporated by an act of parliament in
1750, the Society was a London-based company
modeled after the great chartered trading companies.
Like the British Fast India Company, it was
formed in response to competition from the Dutch,
who then dominated the trade in cod and herring.
Called "white fish," the herring, about a foot long,
was silver sided, the cod, two to over three feet in
length, was white on the belly. These fish were
known to be nutritious, and the fresh head of cod
was thought delicious. Moreover, they were
believed to be inexhaustible. By studying the melt,
the great microscopist Antoni van Leeuwenhoek
estimated that there were more animalcules in a
single codfish than there were people on earth. If
only two males and two females were left in the
sea, in the next season there would be as many cod
as ever. The promoters of the Society reasoned that
since Britain was situated in the "midst of one
continuous Herring Shoal," all that was needed to

Cavendish

revive British fisheries was the "Power and united
Strength" of a trading company. Flourish the
Herring-Fishery!, a new ballad, was sung to the tune
of The Charming Month of May in meetings halls
across London. A good white-fish industry, the
argument went, would empower the kingdom
against France (by insuring a supply of seamen),
improve its moral character (by eliminating the
barbaric practice of impressing seamen), rebuild
the economy in depressed regions like the
Highlands, and provide work for the unemployed
and for children in charity schools (the Society and
the Hospital were made for one another). The
Society was permitted to own ships, build warehouses
and wharves, carry naval staples, regulate trade,
and raise a capital sum for these purposes in the
form of joint stock paying three percent. 7

The officers of the Society, elected for three
years, included a governor, a president, and a
council. We do not know when Charles Cavendish
was elected to the council, but we can imagine why
he would have been interested. First, there was the
connection with the Foundling Hospital, to which
Cavendish, as governor, gave conscientious serv ice.
Then, as usual, there was a family connection.
When the Society was founded. Cavendish was
overseeing the Lowther estates. Sir James Lowther

'Ruth K. McClure, (.'//ram's Children: The London Foundling
Hospital in llu- Eighteenth Century (New Haven: Yale University Press,
1981). 205-18. William Watson, An Account of a Series of Experiments
Instituted villi a Vies' of Ascertaining the Most Successful Method of
Inoculating the Smallpox (London. 17o8). Charles Crcighton, A History
//(Epidemics in Britain, vol. 2: From the Extinction of the Plague to the
Present Time, 2d ed. (London: Frank Cass. 1965), 500. 514.

♦Nichols and Wrav. Foundling Hospital . 298, 554. 413.

Mbid., 131.

"Collitis's Peerage of England Genealogical, Biographical, and
Historical, 9 vols., ed. E. Brydges (London, 1812) 1:356.

'Francis Grant, A letter to a Mem//// of Parliament, Concerning the
Free Hrilish Fisheries (London. 1750), 57. Anon.. The Fisheries Relived:
or, Britain's Hidden Treasure Discovered (London, 1750), 13, 46, 50-52.
By a Trader in Fish, The lies! and Most Approved Method of Curing
White-Herrings, and All Kinds o) White-Fish (London, 1750). Anon., The
Vast Importance of the Herring Fishery, etc. to 'These Kingdoms: As
Respecting the Sational Wealth, Our Nerval Strength, and the Highlanders.
In Three Letters Addressed to a Member of Parliament (London, /l 750/).
Mr. Horslcv, A Translation of the Dutch Placart and Ordinance for the
Government of the Great Fishery (London. 1750). Anon.. Britannia's
Gold-Mine: or, the Herring-Fishery for Ever. A Xew Ballad, to the Tune of,
'There Was a Jovial Beggar, etc. Sung at Draper's- Ha/I, by the Anti-
Galladans; at Merchant-Taylor's Hall, by the Sons of the Clergy; and at the
Spring-Gardens. Vauxhall. To Which Is Added Another Sen- Ballad, on the
S/i/nc Subject, 2d ed. (London. 1750). Britain had three sorts of
fishing, "free." "common," and "several." A person with the rif^ht of
free fishing could take possession offish without title; a free fishery
implied the freedom of fishing with others. William Nelson, The
I ,avs Concerning Game . . .. 4th ed. ( London, 1 75 1 ), 97- 101.

Public Activities

had owned a fishery and a fleet of fifteen ships,
which, Cavendish was convinced, were now
lawfully his. Sir James had belonged to the Society
of Free British Fisheries; in fact, in the list of
nearly seventy charter members, his name came
second, following that of the Lord Mayor of
London. Cavendish was not a charter member but
he may well have become a member when, and
because, Sir James (and Sir William) Lowther
died. 8 As a councillor of the Society, Cavendish
would have been performing a duty, as usual
looking after his and everyone else's interests.

Readers of books lacked a public institution in
London. The Universities of Oxford and Cam-
bridge had libraries, cathedrals had them, wealthy
individuals did too, and there were a few
specialized libraries such as the one for law at the
Inns of Court and the one for science at the Royal
Society. In addition a few small public libraries had
been established in London in the seventeenth
century, but in general, people who were not rich
enough to own their own libraries or did not have a
rich patron or did not belong to a learned profes-
sion did not have access to books. There was a
good deal of borrowing among ordinary persons
with small holdings of books, but what books an
interested person could lay his hands on was up to
chance. In the matter of public libraries England
was a poor cousin to European countries. Italy had
had important public libraries since the fifteenth
century; in Prussia Berlin had had a great public-
library since the late seventeenth century; in
France the royal library in Paris had been open to
the public since 1735, and the Mazarin library
there was nearly as large; and other great European
cities such as Vienna and Munich had their major
public libraries. 9 London, the late-comer, in the
middle of the eighteenth century, acquired its own
in the form of the British Museum.

The British Museum was not primarily a
library, though in the eighteenth century that
became its principal use. Its benefactor was Hans
Sloane, a great collector of natural history objects,
various of which he would bring to meetings of the
Royal Society. So identified was Sloane with his
collection that when he stepped down from the
presidency in 1741, the secretary Cromwell Mortimer
dedicated a volume of the Philosophical Transactions
to him and his "noble and immense Collection."

His natural history collection together with his large
library of books on the subject and on medicine,
inflated by Mortimer to the "most complete in the
Universe," 10 lived on after him as an institution.

By Sloane's will, at his death in 1753, the
nation was offered his collection and books, for a
price. Parliament accepted and decided on a way of
raising the necessary money, a (mildly corrupt, as it
turned out) lottery. In 1754, the trustees bought
Montague House and moved into it Sloane's
collection and in addition the Cottonian Collection
and the Harleian Manuscripts. Montague House,
which was open and free to "all studious and
curious Persons,"" was sometimes referred to at
first as Sloane's Museum, but it would be known as
the British Museum.

Cavendish was not named in Sloane's will as
one of the original trustees, but he was included in
it in a long list of dignitaries, designated "visitors,"
starting with the king and the prince of Wales, who
were charged with watching over Sloane's collection. 12
To get from these important people to the working
people, the librarian and undcr-librarians, parlia-
ment approved a complicated plan. A manageable
but still large number of persons selected from the
larger number of trustees and visitors was directed
to elect fifteen persons. These so-called "elected
trustees" were then to name a standing committee
to meet regularly with the staff and be responsible
for the actual management of the Museum.

The elected trustees were joined by the
president of the Royal Society, then Macclesfield,
as an ex officio member. The connection with the
Royal Society was and would remain close: eleven
of the fifteen elected trustees were Fellows of the

"Sir James Lowther died five years after the founding of the
Society. The original members of the Society are listed in A Bill
I milled an Act for the Encouragement of the British White Herring Industry
(London, 1750). The third member listed, after Sir James Lowther,
was Nathaniel Cur/on, Lord Charles Cavendish's earlier fellow
Member of Parliament from Derbyshire, the county of the duke of
Devonshire. The duke from time to time was party to legal cases
involving fisheries, evidently fisheries of the "several" kind, in
which the owner is the owner of the soil where the water flows.
Stuart A. Moore, A History of the Foreshore and the Law Relating
Thereto . . ., 3d ed. (London. 1888), 720-21.

'Edward Miller, That Noble Cabinet: A History of the British
Museum (London: Deutsch, 1973), 25.

'"Dedication on 31 Dec. 1741, just a month after Sloane's
resignation: PT, vol. 41. for 1739 and 1740, published in 1744. .

"Arundell Esdaile, The British Museum Library: A .Short History
and a Survey (London: George Allen & I'nwin, 1946), 18.

^Sloane's printed will: BL Add Mss 36269, ff. 39-54. A
handwritten list in 1753 of additional trustees includes Cavendish, f. 57.

Royal Society, one of whom was Cavendish, who
was also named to the standing committee, which
met regularly with the staff. Cavendish was among
friends on the standing committee, his brother-in-
law Philip Yorke and his colleagues Watson, Birch,
and Macclesfield. 13

Cavendish was involved in every stage of
preparation for the opening of the Museum in 1759.
He and his committee went to Sloane's house,
where they found the insects in good condition but
some of the birds and animals in an expected state
of decay. They compared the contents of the
cabinets with the catalogues in forty-nine volumes,
and they made comparable inspections of the books
of the several collections. There were endless, tedious
meetings about repairs, insurance, contracts, finances,
and the like. By 1755 Cavendish's name sometimes
headed the list of trustees at the general meetings,
despite the number of peers who could come but
often did not, and whose names would have preceded
his. Attendance at the weekly committee meetings
dropped to five or so, but Cavendish was always there,
and when Macclesfield was not, which was often.
Cavendish presided. 14 Cav endish was a man of public-
affairs with broad intellectual interests and adminis-
trative skill, who could be counted on absolutely.
That was not the least of the reasons why his services
were valued at the British Museum and, in general,
in the affairs of the learned world of London.

Montague House, which earlier had almost
been grabbed up by the Foundling Hospital, was
situated at the north end of town, on one of the
first of the London squares, Bloomsbury, beyond
which lay open fields and then Hampstead.
Bloomsbury Square was then highly fashionable,
home to rich and famous physicians such as Sloane
and Mead. The original house, designed in the
French style for Ralph, later first duke of, Montagu
by the versatile curator of experiments of the Royal
Society Robert Hooke, had burned down, and the
duke had replaced it by a new but similar house
resembling a contemporary Parisian hotel. With its
imposing facade, colonnades, an entrance topped by a
cupola, and wings extending to the front to form a
grand courtyard, and with an interior of spacious and
lofty apartments and wall paintings, this mansion was
in itself an expression of the grandeur of the idea of a
great library and scientific collection in the British
metropolis. Given the load it was to bear, of equal
significance was the sober ev aluation by the standing

Cavendish

committee, to which Cavendish belonged, of the
house as a "Substantial, well built Brick Building."
Seven and a half acres of garden came with it, to
which Cavendish's friend and fellow trustee
William Watson devoted a great deal of care. 15

Montagu House had been unoccupied for
several years and was generally run down; in the
end, no expense was spared to restore the house to
its former glory. Countless times Cavendish went
up the elegant main staircase to the upper floor
where the trustees met and where the manuscripts
were housed. Less imposing was the reading room
in the basement, a dark space containing a
wainscot table and twenty chairs." 1

The collections of the British Museum
were dedicated to the "Adv ancement and Improve-
ment of Natural Philosophy and Other Branches of
Speculative Know ledge." If the Museum sounded
like the Royal Society, it was not by accident. Its
scientific ambition is evident in the high, if not
actually incredible, qualifications desired of the
head of staff (who was, however, called Principal
Librarian rather than Keeper of the Collections, the
title of a book man rather than a man of science). He
was to be studious, learned, educated as a physician,
versed in mathematics, a judge of inventions, able
to carry on conversation with the learned in their
fields, and competent to write and speak French
and Latin and correspond with foreigners. 17 There
were disqualifying criteria too, which were not
mentioned. 18 Plenty of persons believed they fit

"A. E. Gunther, "The Royal Society and the Foundation of the
British Museum. 1753-1 781," Notes and Records of the Royal Society of
London 33(1979): 207-16, on 209-10.

14 Thomas Birch's minutes of the meetings of the Trustees of the
British Museum: BL Add Mss 4450. ff. 1 and following. Minutes of
the General Meetings anil the Standing Committee Meetings of the
Trustees of the British Museum, ibid., 4451. ff. 3 and following.

"Miller, Noble Cabinet, 50-54.

" Ksdaile. The British Museum Library, 3H-40. Edmund William
Gosse, Gray, new ed. (London: Macmillan. 1906), 141—42.

''"Qualifications and Duty Required in the Principal Librarian,"
BL Add Mss 4449. f. 108. "Rules Proposed to Be Observed in
Making the Collections of Proper Use to the Publick by Way of
Resolutions in a General Meeting of the Trustees," ibid., f. 1 15.

'"Emanuel Mendes da Costa applied for an under-librarian's job at
the British Museum, w ith these credentials: he was a long-time Fellow
of the Roval Society, an expert on fossils, and fluent in all of the main
languages. Letter to Lord Hardwicke. 4 Feb. 1756. BL Add Mss .16269.
f. 100. William Watson considered da Costa to be eminently qualified,
but his "religion is an unsurmountable object." Letters to Archbishop
of Canterbury, 21 June 1756. and Lord Hardwicke, 22 June 1756, BL
Add Mss 36269, ff. 139-42, 144-45. Da Costa could not have been sur-
prised. A few years later he asked Thomas Birch if it w as "obnoxious to the
Society that I (as by Profession a Jew ) can put up for Hawksbcc's place"
in the Royal Society. Letter of 1 7 Jan. 1763, BL Add Mss 431 7. f. 113.

Copy rig hi

Public Activites

the bill and offered eredentials to prove it. Gowin
Knight, who was chosen principal librarian,
presented himself as a physician who had devoted
the greatest part of his life to the "pursuit of
natural Knowledge" 14 (the evidence, his powerful
artificial steel magnets, he brought with him to the
British Museum.) 20 Matthew Maty, De Moivre's
friend, who was appointed an under-librarian, had
accomplishments equally impressive. He had
taken an M.D. under Boerhaave at the University
of Leyden; he had studied natural philosophy, and
he had been taught mathematics by his father; he
had wide-ranging foreign connections as editor of
the Journal Britannique, and he spoke French and
Dutch. 21 Soon after joining the staff of the British
Museum, Maty was elected secretary of the Royal
Society. Another of the under-librarians was
Charles Morton, physician to the Middlesex and
Foundling Hospitals, who also had taken his M.D.
at the University of Leyden and who too was a
secretary of the Royal Society, and like Maty he too
one day would become principal librarian. 22 A third
undcr-librarian, James Fmpson, was in charge of
Sloane's natural history collection. As each under-
librarian had an assistant, the staff was sizable and
"unexceptionable." That was William Watson's
opinion on its competence; its "disposition," however,
was another matter. Librarians and assistants were
not on speaking terms; insubordination was
rampant; ill-will persisted for years. Watson
analyzed the conflict in terms of turf, 25 and the
poet Thomas Gray, one of the first users of the
library of the British Museum, compared the
rebellious factions to fellows of a college: "The
whole society, trustees and all, are caught up in
arms." 24 The scientific use of the collections was
not great at first. 25 People came to the Museum to
read, and for a time, a two-month reservation was
required even to secure a seat, but before long the
reading room proved ample; after the Museum had
been open a few months, Thomas Gray found
himself one of only five readers, the others being
the antiquarian William Stukeley and three hacks
copying manuscripts for hire. 26 Readers were
admitted for six months at a time, upon rec-
ommendation; members of the Royal Society and
other learned bodies were admitted without rec-
ommendation. In 1759, the first year, beside men
of historical and literary interests, such as Gray and
David Hume, men of science, such as Watson,

Heberden, and John Hadley, visited the reading
room too. 27 The library became the national library,
and the natural history collection evolved into a
great research center. This successful institution
had no more assiduous early administrator than
Lord Charles Cavendish.

Westminster Bridge

The early eighteenth century saw both the
rapid improvement of roads through turnpiking
and the beginning of bridge building on a large
scale. The urgency was due to London, far and
away the largest city in the world, the demands of
which on the still largely agricultural nation were
vast and insatiable. Herds of cattle and flocks of
geese were driven down the turnpikes to feed the
concentrated mass of humanity on the banks of the
Thames. The streets of the city were filled with
mud or dust depending on the weather, and to
riders of carriages they were bone-jarring. Here and
there stairs led down to the river, where cursing
boatmen ferried paying passengers to the opposite
bank. London Bridge, the one bridge in the city,
was medieval, dangerous, and congested, built up
with houses. Ideas for improving transportation in
London by a second, modern bridge had been
around since Elizabethan times, successfully resisted
by impecunious monarchs, fierce watermen
defending their traffic from ruin, and parties

"Gowin Knight to Lord Hardwickc, 22 Sep. 1 754, Bl. Add Mss
36269, ff. 29-30.

20 For placing his magnetic apparatus, Gowin Knight requested
that a passage five feet wide be taken from two rooms in the British
Museum. BL Add Mss 36269, f. 134.

"J. Jortin to Lord Hardwicke, n.d. and 12 Feb. 1756, BL Add
Mss 36269, ff. 104-7.

""Morton, Charles," D.VB 13:1047-48.

-'The under-librarians were naturalists, and their assistants were
antiquarians, an unworkable combination. The different parts of the
British Museum required different talents, which had to be properly
assigned. Watson pointed out: "We have an extensive collection of
the productions of nature & of art: a very large medical &
philosophical library; as well as one relating to antiquities, & a vast
collection of coins. . . ." The friction among the staff was rooted in
this fact: "it must require a great length of time for any person to
have a competent knowledge of any one branch of the museum &
unless he be acquainted with it, he will be but little qualified to
instruct others." The proper persons had to be matched up with the
proper subjects. Typical good sense from William Watson to the
Archbishop of Canterbury, 21 June 17.56.

■^Gosse. Gray , 142.

- S A. K. Gunther, The Founders of Science til the British Museum,
1153-1900 (Halesworth: Halesworth Press, 1980), 10-11.
' Gossc. Gray, 142.

'""Persons Admitted to Reading Room Jan. 12. 1759 to Mav II.
1763," BL Add Mss 45867.

Cavendish

expressing a variety of fears, such as commercial
competition, armed rebellion, and the falling down
of London Bridge once it was neglected for a rival. 2 *

Nobody knows why Lord Charles Cavendish left
politics to immerse himself in scientific and
learned affairs. It is, of course, not hard to imagine-
that after so many years in parliament he had
grown tired of politics. He was, after all, politically
unambitious and only dutiful. Whatever his reasons
for desiring a change, he lived in a time and place
that invited experiment in life as well as in the
laboratory; England in the eighteenth century
encouraged individual self-expression and personal
autonomy.- 9 For Cavendish, Westminster Bridge-
proved to be, in effect, a bridge between his earlier
political career and his later one outside of politics.

Renewed energy behind the proposal of a
new bridge at Westminster took the form of two
petitions to parliament in 1721, presented by
Westminster and the Home Counties. James
Thornhill, Member of Parliament and Fellow of
the Royal Society, produced a plan for a bridge at
Westminster and enough support for a parliamentary
committee to recommend proceeding." 1 A bridge-
bill was draw n up by William Pulteney, chairman of
the committee, and Samuel Molyneux, Fellow of
the Royal Society, astronomer, and secretary to the
prince of Wales. Molyneux spoke for the prince's
interest when he pointed out to the Commons that
the "building of the bridge would be agreeable to
his highness and be convenient for his family's
passing and re-passing to his country house." 31 On
the advice of Lord Burlington, architectural in-
novator and Fellow of the Royal Society, the com-
mittee commissioned the architect Colin Campbell
to design the bridge. Burlington then consulted
"two eminent mathematicians" and prominent
Fellows of the Royal Society Fdmond Halley and
John Arbuthnot, who gave the bridge the go-ahead.
The House of Commons debated the bridge bill
but then dropped it, probably for political reasons,
since Walpole, who favored the bridge and was on
the committee, was well hated by then. 52

The project was revived, this time for good,
in 1733, when a "Society of Centlemen," busi-
nessmen and the like who could afford the large-
expense of a petition, began meeting at Horn
Tavern in New Palace Yard, Westminster. The pro-
moters ordered the river "measured and sounded,"

and they solicited maps and surveys from Charles
Labelye, the future engineer of the bridge. They
asked the architect Nicholas Hawksmoor to
prepare a design, and in 1735 a stone model of the
bridge was shown to the prince of Wales and the
House of Commons." (Vying for the commission
was Batty Langley, who at about this time was
employed by Cavendish's father-in-law, the duke
of Kent; turned down, Langley gleefully pub-
lished a pamphlet at the time when the construc-
tion of the bridge was having its worst problems,
in 1748, A Survey of Westminster as ''lis Now Sinking
into Ruin. 34 )

In February 1736 a renewed petition for the
bridge was submitted to the House of Commons,
which again appointed a committee. This committee,
w hich could hear testimony of any kind, chose J. T.
Desaguliers on the subject of the "proper
Instruments for boring the Soil under the River
Thames," undoubtedly hoping this way to avoid
the commercial controversy that had upset bridge
plans in the past. They had to decide several
matters: if a bridge was technically feasible; if its
foundations and piers would affect the flow of the
river and its traffic; and, finally, which site would
be best. All of these matters were fraught with
complications."

The Westminster Bridge bill in May 1736
set up a large body of commissioners, about 175 in
number. They were not necessarily Members of
Parliament, although a good proportion of them
were. They included such obviously useful persons
as the director of the Bank of England and the
Members of Parliament from Westminster. They
included as well dukes, bishops, and admirals, who
were useful in other, more or less obvious ways.
And there were a good many Fellows of the Royal
Society, such as Cavendish and Macclesfield. The
first meeting was held in June, with Lord Sundon

iN R. J. B. Walker, Old Westminster Bridge: The Bridge of Fools.
(Newton Abbot: David and Charles, 1979), 12-32.

29 Lawrence Stone, The Family, Sex and Marriage in England
IS00-1800 (Harmondsworth: Penguin Books, 1982), 151-52, 179.

l "Walker, Old Westminster Bridge, 45—47.

"Romney Sedgw ick, 'The House of Commons 1715-1754, 2 vols.
(New York: Oxford University Press, 1970) 2:263.
"Walker, Westminster Bridge, 47-49.
"Ibid., 27, 50-51,61.

^Howard Montagu Colvin, A Biographical Dictionary of British
Architects, 1600-1840, rev. ed. (London: J. Murray, 1978), 355. Walker,
Old Westminster Bridge, 1 82-83.

« 1 6 Feb. 1 736 ( 1 735 ), HCJ 22:569.

Copyrlghied mater

Public Activites

in the chair and about fifty commissioners
attending. One of the two officers appointed at the
meeting was another Fellow of the Royal Society',
Sir Joseph Ayloffe. The commissioners viewed the
models of the bridge that had been exhibited in
the Commons, and they set up a lottery with the
Bank of England to finance the construction. 36

The lottery did not catch on at first. In July
1736 the Bank of England reported that so far only
about one fifth of the tickets had been sold,
leading knowledgeable observers to say that that
was the "end of that scheme for raising money." Of
the original, large body of commissioners, only one
or two now came to the meetings, too few for a
quorum, and for the likely reason that there was
nothing for them to do. The upshot was a second
bridge act, which added incentives to the lottery."

Cavendish was present at the meeting of
the commissioners in June 1737 to consider the
reality, the actual bridge in design stage. Thomas
Ripley, comptroller of the King's Works and
protege of Walpole, presented plans for a stone
bridge at a cost of 75,000 pounds, a figure which
got bigger with subsequent discussions, and he also
gave an estimate of 35,000 pounds for an alternative
timber bridge at the Horseferry. The commissioners
liked the lower estimate of the timber bridge.™

Bridge-builders followed parliament's delib-
erations closely, eager for the commission for this
remunerative project; it took only two weeks for
the first plans to be submitted, probably pulled out
of the drawer. The Royal Society was kept
informed; Thomas Innys showed the Society a
model of his invention of a machine for laying the
foundation of the piers of the new bridge. To
decide on technical matters of this sort, in June 1737
the bridge commissioners formed a committee of
thirteen, the so-called committee of works. Cav-
endish was appointed to it, as were several other
Fellows of the Royal Society, though William Kent,
the famous architect, was perhaps the only mem-
ber of the committee with obvious qualifications. 39
Now both a commissioner and a committeeman for
the bridge, Cavendish took his duties with his cus-
tomary seriousness.

The works committee resolved to consider
economical wooden bridges only, but it and the
commissioners took an interest all the same in the
stone-bridge advocate Labelye, especially for his
method of laying the foundations of the piers,

which would work for either a timber or a stone
superstructure. 4 " Labelye had credentials different
from those of his competitors, the best known of
whom all came from the side of architecture and
seem to have had no engineering experience.
Labelye, by contrast, was not an architect at all but
evidently had some training in engineering and
surveying. The Commons treated him as an expert
"engineer," calling on him to testify on the bridge
before their own petition committee along with J.
T. Desaguliers, who claimed Labelye as his
"disciple" and "assistant." 41 Like Desaguliers,
Labelye was of Huguenot origins. Educated in
Ceneva, he had settled in England, where he
became involved in such projects as draining the
fens and improving harbors. 4 - Not himself a Fellow
of the Royal Society, he was a friend of a good
number of scientists. In the midst of building the
bridge (to get ahead of our story) he wrote from
Westminster to the president of the Royal Society,
Folkes, sending him a calculation having to do
with the card game whist. 43 The prospect of a
gambling bridge- builder could be upsetting, but
Labelye 's calculation was only an exercise in the
doctrine of chances. Labelye was a good enough
mathematician for Desaguliers to publish
Labelye's mathematical investigation of the vis
viva controversy in mechanics. 44

An unusually large number of commis-
sioners, fifty-four, met in February 1738 to decide-
where the bridge was to be built. A petition for
locating it was then presented to the Commons,
which acting as a committee decided that it should
be at Woolstaple, a short distance from the original

"'Walker. Westminster Bridge, 63-67.

"Westminster Bridge, Minutes of the Bridge Commissioners,
vol. 1: June 1736-Fcb. 1740. Walker, Westminster Bridge, 73^*.
'"Walker, Westminster Bridge. 78-79.

'''Besides Cavendish, three others on the committee had been
Fellows of the Royal Society since the 1720s. They were the chairman
of the committee, Joseph Danvers, M.P., a lawyer by training and now
a landowner; David Papillon, M.I'., practicing lawyer; Thomas
V iscount Gage, M.P., from 1743 master of the household to the prince
of Wales. Walker, Westminster Bridge, 79, 86 n.7.

*5 Aug. 1737, Minutes of the Committee of Works, vol. I: Aug.
1737-Sep. 1744, Public Record Office, Kcw, Work 6/39. 31 Aug. 1737
and 3 May 1738, Bridge Minutes.

*' 16 Feb. 1 736 ( 1 735), HCJ 22:569. J. T. Desaguliers, A Course of
Experimental Philosophy, vol. 2 (London, 1744), 506.

■"Walker, Westminster Bridge, 83-86.

"Charles Labelye to Martin Folkes, 22 Mar. 1742/41, Folkes
Correspondence. Royal Society.

""Charles Labelye to J. T. Desaguliers, 15 Apr. 1735, published
in Desaguliers. Course 1:11, 89-91.

Cavendish

site at New Palace Yard. The third bridge act,
fixing the location, became law in May. 45

The commissioners hired the "foreigner,"
Labelye, to build stone foundations for a bridge
that still could be made of wood or stone. 4 '' Wood
w as the material of ehoiee beeause it was cheaper,
but there was widespread feeling that a wooden
bridge at Westminster would be ridiculous; the
dignity of London and Westminster demanded a
stone bridge. A formal decision would have to be
made, but for the time being the commissioners
busied themselves with appointments. Richard
Graham, a maker of scientific instruments and
Fellow of the Royal Society, was named surveyor
and comptroller of the works. 47 Thomas Lediard,
who was named surveyor and agent, would deal
with the owners of the property condemned to
provide approaches to the bridge. 48 Lediard was
elected to the Royal Society in 1 742.

In June 1738 the commissioners reappointed
thirty of their number to the works committee. At
the first meeting that month, only six attended.
Cavendish one of them, along with a newcomer,
the earl of Pembroke, w ho w as to make himself the
heart and soul of the project. Coming from a
cultured family, Pembroke had a strong interest in
architecture and considerable experience, having
helped build houses for George II and the duchess
of Marlborough. Pembroke was elected to the
Royal Society in 1743. At another meeting of the
commissioners that month, contracts were decided.
The masonry contract for the center piers went to
master masons Andrews Jeolfe and Samuel
Tufncll; the former had worked on fortifications,
and the latter was the latest representative of a
prestigious family of Westminster masons. Jeolfe
and Tufnell were guests at the Royal Society
occasionally but never members, very knowledge-
able practical men who were perhaps insufficiently
"learned." None of the architects and builders on
this project, even the best known, seems to have
made it into the Royal Society, but perhaps none-
wanted to be there. 49

Once construction began, opposition to the
bridge turned violent. At a meeting of the commiss-
ioners in August 1738, Cavendish heard the report.
Labelye was putting in place the pile-driving
engine, a machine for lifting and dropping the
heavy ram, powered by three horses (and designed
by the watchmaker James Vauloue, a friend of

Desaguliers). Angered over the threat of losing
their trade to the bridge, the watermen ran their
barges into the boats moored beside the engine.
The commissioners ordered Ayloffe to advertise
the part of the bridge act that legislated the death
penalty for anyone found guilty of sabotaging the
bridge works. That done, the new engine was tried
without incident and found to work. In December
of that year, Richard Graham brought Vauloue and
his model of the engine to a meeting of the Royal
Society, which then invited Vauloue to write it up.
He did not do it, but when Desaguliers published
the second volume of his Course of Experimental
Philosophy in 1744, he included a description and
plate showing the mighty engine. Labelye too
published an account of the engine. When in
January 1739 the foundation for the first pier was
finished, Pembroke laid the first stone "with great
Formality, Guns firing, Flags displaying." 50 In 1750
the bridge was at last opened to traffic. Up to the
final year, Cavendish attended the meetings of the
commissioners. He had done much of the quiet
work to bring off this wonder of the modern world.

Technical problems had dogged the construc-
tion all the way, the most damaging (in every sense)
being the sinking of the bridge. The unhappy
watermen burst into cheers as they watched the
bridge start to go under, as many as four inches in a
night. 51 People sat up to watch it and to be able say
"What kind of a Night the Bridge has had." 5 -' The
bridge was supposed to bear 12(H) tons, but when it
was loaded with only 250 tons of cannon, as a test,
it sank. 55 It kept on sinking — "Westminster-Bridge
continues in a most declining Way," Thomas Birch
reported to Philip Yorke — as one of the piers
subsided into the river bed. 54 Possibly it was

4 "\Y.ilkcr. Westminster Bridge, 80.
«*Ibid., 82.

47 K. (>. R. Taylor. The Mathematical Practitioners of Hanoverian
England 1714-1X40 (Cambridge: Cambridge I'niversity Press.
1966), 160.

■•"Walker. Westminster li ridge . 99.

*>Colvin, Dictionary, 281. 318-19, 628. Walker, Westminster Bridge,
67-68, 88-91.

s "Walker. Westminster Bridge, 91-95. Desaguliers, Course 2:417-18.

5'Thomas Birth to Philip Yorke, 12 Sep. 1747, BL Add Mss
35397, ff. 72-73.

"Thomas Bireh to Philip Yorke, 19 Sep. 1747. BL Add Mss
35397, ff. 74-76.

"Thomas Bireh to Philip Yorke, 11 June 1748. BL Mss Add
35397, ff. 114—15.

"Thomas Bireh to Philip Yorke, 18 June 1748. BL Add Mss
35397, f. 116.

Public Activites

sabotaged, but whatever the cause, the pier had to
be rebuilt, which took extra years. The wait was
worth it. There had not been a new bridge across
the Thames in London since the London Bridge in
the twelfth century. Spanning 1200 feet, the
Westminster Bridge was a worthy successor: this
bridge, built of Portland and Purbeck stone,
heavily delicate, was a monument to both
engineering and architectural grace. 55

In a report on the bridge halfway through,
Labelye wrote that the bridge commissioners
"have nothing, and can expect nothing, but
Trouble for their Pains," and he admired their
selfless "publick Spirit" and "Patience." 56 Labelye
was right about a few of the commissioners such as
Cavendish. Cavendish devoted a tremendous
effort to the bridge while at the same time carrying
out his parliamentary duties. In 1739, in the third
year of the bridge, for example, in the Commons
he served on twenty-four committees; and he also
went to nineteen meetings of the Westminster
Bridge commissioners. In the middle years of the
construction, he rarely missed a meeting of the
commissioners or of its works committee. In
addition he came fairly regularly to a third kind of
meeting, that of a small committee of accounts for
the bridge, often chairing the meeting. 57 In 1744,
Cavendish attended 25 out of 26 meetings of the
commissioners and 18 out of 19 meetings of the
works committee; this was his most conscientious
year, but other years came close to this one. By this
time he was also active on the council of the Royal
Society. He saw the Westminster Bridge through to
the end, as he did any project he undertook. He
worked well with all kinds of persons in this project.
He brought the same combination of political,
administrative, technical, and accounting skills to
his organizational work for the Royal Society.

Scientif ic A dministration

We begin this discussion of Lord Charles
Cavendish's administrative work by recalling some
basic facts about the running of the Royal Society
at the time of his election. By a royal charter of
1663, the Society was constituted a self-governing
corporation. Every St. Andrew's Day, November
30, the members elected from their own number a
council of twenty-one, from whom they elected a
smaller number of officers, president, treasurer,
and two secretaries. The president chose one or

more vice-presidents to sit in for him when he w as
absent. (Macclesfield was absent often and needed
vice-presidents; in 1755 he appointed Cavendish,
who joined the four he had already appointed.) To
ensure that the council did not become fixed and
at the same time to give it continuity, ten of its
members were newly elected each year while
eleven were kept on from the old council. The
entire government of the Society was invested in
the council and president, who were assisted by a
person responsible for foreign correspondence and
translations of foreign papers. New members were
elected by two thirds of the members who were
present at the meeting, and the election of officers
was by simple majority. 58

In 1736, eight years after his election to the
Society, Cavendish was elected to its council for
the first time. He was elected next in November
1741, and for the next twenty years he was on the
council every year with the exception of 1753,
when family business called him away. He served
four more, non-consecutive terms on the council,
his last in 1769, in which year he served on the
council together with his son Henry. Henry would
have an even longer record of service; combined,
their membership on the council would span seventy-
three years, with few interruptions. For many years
Lord Charles was also a vice-president.

The Royal Society was now in its third
home, in Crane Court, a quiet, central location.
The front of the house faced a garden, the back a
long, narrow court. Up one flight of stairs and
fronting the garden was the meeting room, about
the size of a modern living room.

The Society as a whole met weekly except
during Christmas and Easter and the long recess in
late summer, about thirty times a year in all. How
often the council met depended on how busy the
Society was and on the energy of the current
officers. Ordinarily it met six or fewer times a year
toward the end of Folkes's presidency in the late
1740s, and eight to ten times under Macclesfield in

"Summerson, Georgian London, 1 13—16.

•^Charles Labelye, The Present Slate of Westminster Hritlgf
(London, 1743), 24-25.

"Minutes of the Committee of Accounts, vol. 1: I73K-I744.
Public Record Office, Kcw, Work 6/41.

™This information is from the Royal Society's Minutes of
Council. In connection with recovering arrears of members, the new
statutes of the Society were drawn up: Minutes of Council .V S(M>1
(20 Aug. 1730).

Cavendish

the 1750s, but it met twenty-two times in 1760
during preparations for observing the transit of
Venus the following year. The president presided
over the meetings both of the council and of the
ordinary membership. Presidents before Newton
rarely eame to council. Newton came all the time,
even changing the day of the meetings of the
council to accommodate his schedule. His
precedent was followed, with decreasing rigor, by
his successors: Sloane missed only H out of 105
council meetings in his fifteen years as president;
his successor, Folkes, missed one quarter of his;
and Folkes's successor, Macclesfield, missed about
a third of his. Administrative continuity depended
increasingly on a small number of council members,
none of whom was more dependable than
Cavendish. Cavendish's first term on the council
was under Sloane's presidency, in 1736, and this
time he missed a good many meetings, perhaps
because he found work on the council difficult to
accommodate to his political duties. He did not
return to the council until six years later, the year
he stepped down from parliament, which was also
the beginning of Folkes's presidency. Now
Cavendish's attendance picked up; for the next six
years he came to two out of three meetings, and
after that he was almost never to miss a meeting.
Frequently only a half dozen members attended
council meetings, a meager number considering
that it included the two secretaries and usually the
president; ten or so were a better turnout, hut
whatever the number, Cav endish was one of them.
To give an idea of his commitment: in the five
years from January 1748 through November 1752,
he attended every one, in all tw enty-seven meetings;
in the eight years from December 1755 through
November 1761, out of eighty-seven meetings, he
attended seventy-eight (at least, since he may only
hav e been late sometimes, and not listed). Only two
Fellows came close to matching Cavendish's record
of attendance at council, the two secretaries of the
Society, who had no choice short of neglecting their
duties: Peter Davall from 1747, and Thomas Birch
from 1752. One other councillor came regularly
over a long period, the eminent barrister James
Burrow, who like ( Charles Cavendish was sometimes
temporary president of the Society during a vacancy. 5 ''
Cavendish's contribution to the running of
the Royal Society is more remarkable when his rank
is considered. The minutes of the council always

listed Cavendish first after the president, except on
occasion when Macclesfield (before he was
president) was there, and later Morton, both carls
(this protocol ceased after 1760 when the councillors
were listed alphabetically). Council members in the
1740s were professionals and gentlemen, not
aristocrats. Macclesfield was a notable exception,
but barely, since he was only the second earl, and his
father was a lawyer. The duke of Richmond, Charles
Lennox, attended one council meeting in 1741, the
earl of Abercorn, James Hamilton, attended three
times in 1743, and that is about it. At this time one
seventh of the membership of the Royal Society
was aristocratic, so Cavendish was not unusual for
supporting science. What set him apart was his
solicitous attention to the affairs of the Society. 60

During his long service in the Royal
Society, Cavendish never initiated an important
change in the way things were done. He was rather
the man to second a motion by a more assertive
leader. Just as his family made rulers but were
themselves not rulers, Cavendish was content with
the job of vice-president. When Folkes was sick in
1752, Cavendish often took the chair,' 1 ' and it was
he who informed the Society that Folkes was
stepping down/' 2 Folkes's successor, Macclesfield,
was an initiator of change, and Cavendish helped
him to achieve his goals. Early in 1752 Macclesfield
asked the council to consider the way papers were
chosen for publication in the Philosophical Trans-
actions. There had been a committee of papers, but it
had not decided which papers were to be published/' 5
One of the secretaries had run the journal, making
the decisions on his own though probably taking

"'Information from the Royal Society, Minutes of Council.

'■"From an inspection of persons attending council meetings
during Cavendish's tenure: Royal Society, Minutes of Council 3. Bound
with the Minutes of the Committee of Papers is a printed membership
list for the Society in 1749. The total British membership then was
around 34(1, and of these around 45 were aristocratic, counting bishops
and persons like Cavendish with the courtesy title "Lord."

'''In 1752 Cavendish chaired five meetings of the council and
frequently the ordinary meetings of the Society, alternating with
James Burrow, Lord Willoughby, James West, and Nicholas Mann.
Royal Society, Minutes of Council 4 and JB 21.

'-'In this event. Cavendish was the one to make a motion, re-
turning thanks to Folkes. Royal Society, JB 21:195-96 (30 Nov. 1 752).

^Cavendish was present on 30 Oct 1749. "At a Committee for
Reviewing the Papers." "Minutes of the Royal Society," vol. 2. Birch
Collection. BL Add Mss 4446. The earlier Committee of Papers met
annually to preserve the papers. A new kind of committee w as called
for by the natural historian John Hill's published criticism of the
Society under Folkes in 1751.

Copy rig hl«i material

Public Artivites

into consideration requests by individual members.
This one-man show was to end: for the "credit and
honour of this society," henceforth decisions about
publication were to be made by a committee. The
committee had to be prestigious; the council
declared that the president, vice-presidents, and
the two secretaries were to be on it and that no
decisions on papers could be made without a
quorum of five. For advice on particular papers,
authorities outside the committee could be brought
in by request of a majority of the committee. In
committee, any paper was to be read in full if a
member desired it, and then without "debate or
altercation." Finally a vote was to be taken, by
ballot, so as to "leave every member more at liberty
to fully declare his opinion." Since the decision to
publish a paper was a recognition not every author
received, the new committee had a sensitive
assignment/' 4 Macclesfield (correcting himself)
said that the Society had not "usually meddled" in
the selection of papers to be published. That it had
meddled at various times in various ways, he now
conceded; what was going to change was that it
would meddle in a systematic and accountable way.
Cavendish joined Macclesfield in proposing amend-
ments, and on 26 March 1752 the new statutes
were passed by the council. 65 With Cavendish in
the chair, Philip Yorke proposed that for the time
being the council be the "committee of papers,"
which was agreed to. 66 The Philosophical Transactions
was now wholly under the direction of the council
and for the "sole use and benefit of the Society,
and the Fellows thereof." 67 The readers of the
journal were informed of the takeover by the
council in an advertisement. In April 1752, the
committee convened for the first time, Charles
Cavendish presiding. Macclesfield came to the first
three meetings, but this mover and shaker dropped
out once he saw that his plan was working; at the
end of the year when he became the new president
of the Royal Society, he started coming around
again. Cavendish chaired all of the meetings but
one through November 1752.

By mid century the time-consuming experi-
mental demonstrations at the meetings were becom-
ing a thing of the past, leaving more time for the
reading of papers. The work of the papers committee
was correspondingly demanding. In the years just
before 1740 the number of papers reached a peak
of well over a hundred per year on the average.

After that, the number fell off, but slowly, and the
load remained great through Cavendish's years on
the committee. It should be said that the number
of papers is not a particularly good measure of the
committee's work, since as the papers became
fewer, they became longer, tending to the large,
interpretative syntheses of facts of Henry
Cavendish's time. 6 * At the time the committee of
papers was formed, there was a backlog. The com-
mittee went through the papers chronologically,
beginning with January of the previous year, 1751,
taking several meetings to get through that year. At
the first meeting the committee approved 16 papers
for publication, at the second meeting 15, and at the
third 24, and so it was getting more efficient, though
in some later meetings it got through fewer. Daniel
Wray, who began coming at the second meeting,
wrote to Philip Yorke of their "diligence, as members
of the Committee of Papers," 6 '' and we can believe it.

The committee of papers met four to six
times a year. The usual attendance was about four
persons in addition to the two secretaries, who
were required to be there, and the president, when
he came. In 1753 Cavendish was not on the
committee, as he was not on the council owing to
family affairs. When he was returned to the council
in 1754, he attended every meeting of the com-
mittee, which remained his habit in the years
following. He was by far the most faithful member
of this committee. After Cavendish Burrow came
most often to the meetings. Watson and Bradley
came occasionally, and other members came and
went. Cavendish's tenacity set an example for his
son Henry, who was to be an unfailing laborer for
this committee in his time. 7 "

To evaluate critically every paper that came
before the Royal Society was an excellent way to

M Macclesfield's motion on the publication of papers was made
on 23 Jan. 17.S2 and spelled out on 15 Feb. 1752. Royal Society.
Minutes of Council 4:49-53.

"Royal Society, Minutes of Council 4:55. 64 (20 Feb. 1752).
71-75 (19 Mar. 1752), 83 (26 Mar. 1752).

^Royal Society, Minutes of Council 4:64 ( 27 Feb. 1 752) .

"Royal Society, Minutes of Council 4:76 (19 Mar. 1752).

''"Raymond Phineas Stearns. Science in the British Colonies of
America (Urbana: University of Illinois Press. 1970), 97-98.

"'Daniel Wray to Philip Yorke, 5 July 1752, Hardwickc Papers,
BL Add Mss 35401. f. 157.

'"Rough notes of the meetings of the Committee of Papers
taken by Thomas Birch, one of the secretaries, in "Minutes of the
Royal Society," vols. 1 and 2, Birch Collection, BL Add Mss 4445
and 4446.

Cavendish

keep abreast of everything that went on in scienee,
good and bad, but we believe that Cavendish's
main motivation was sen ice to the Society. In a
variety of ways the Society rationalized its
procedures at this time, 71 and those that applied to
the Philosophical Transactions were especially-
important, since its contents were the public record
of the Society. Because the external authority of
the Society derived mainly from its journal, the
selection of papers to publish was a high
responsibility. Cavendish got the committee off to
a conscientious start in its first year.

In connection with the transit of Venus in
1761, the minutes of the council recorded scientific
matters for the first time. Halley had foretold the
transit and with it the opportunity for measuring
the distance of the earth from the sun, the standard
by which the distances of the other bodies of the
solar system were expressed. Preparations were
made long in advance, since world-wide expedi-
tions were needed to get the best view of Venus
crossing the solar disc. From the summer of 1 760 to
early 1763, the council was almost exclusively
occupied with the project, energized as never
before by its complex planning. The East India
Company and the admiralty were enlisted, the
treasury was approached, and money was received
from the king, instruments were specified,
observers were selected, and sites of observation
were determined. During the flurry of activity in
1760, Cavendish was sometimes in the chair. In
addition to dealing with all of the council matters
having to do with the expeditions, he was involved
in the scientific work at even, level from the
examination of a faulty instrument 7 - to the w riting
of a synopsis of the completed observations of the
transit. 71 ( The council was preoccupied with
instruments at this time; while the project for
observing the transit of Venus was in progress,
John Harrison's clock for finding longitude at sea
came before the council, which recommended a
trial at sea, on a voyage to Jamaica. 74 ) Soon after the
transit of Venus, another expedition was planned:
two of the observers of the transit, Charles Mason
and Jeremiah Dixon, were commissioned by the
Royal Society to measure a degree of latitude
between Maryland and Pennsylvania, and Caven-
dish was on the committee to draw up their
instructions. 7S There was little of significance done
officially at the Royal Society in the middle of the

eighteenth century in which Cavendish was not
fully involved.

Meetings of the council typically had to do
with money: bills from printers, bookbinders,
solicitors, and instrument-makers, payment of debts,
insurance on the houses owned by the society. Past
India Company bonds, salaries; it was pretty much
the same, and it was endless. Besides dealing with
these matters routinely as they came up in council.
Cavendish went over them all again as auditor;
nearly every year he was appointed one of a
committee of auditors of the treasurer's accounts,
often together with William Jones until Jones's
death in 1749. Cavendish was on call as the all-
purpose, responsible Fellow of the Royal Society, as
his son Henry would be after him.

As we have seen, Cavendish's first recorded
scientific work was in astronomy, and we find him
active in astronomical administration through the
Royal Society's oversight of the Royal Observatory.
He was involved in drawing up the regulations for
the observatory, for one thing. 76 In 1765, by warrant
from the king, the president of the Royal Society
together w ith other Fellows of the Royal Society
were charged with making regular tours of inspec-
tion of the instruments of the Royal Observatory 77
Cavendish was for several years one of a small
number of Fellows who made the so-called

"On keeping records of all sorts: "Proposal Concerning the
Papers of the Royal Society" /by Macclesfield, presumably/. BL Add
Mss 4441. The Society eliminated unnecessary duplication and
classification in its record keeping: it was found that papers
presented before the Society ended up in two kinds of books, while
only one. the minutes of ordinary meetings, was needed. Royal
Society. Minutes of Council 3:2K5 (12 July 1742).

72 Royal Society. Minutes of Council 4:333-34 (27 May 1762).

"'Thomas Birch to Philip Vorke. Viscount Royston, 20 June
1761. BL Add Mss 35399, f. 207.

Royal Society, Minutes of ( louncil 4 (25 June 1 761 ).

75 Royal Society, Minutes of Council 4:43 (23 Oct .1764). .

">Lord Morton to Thomas Birch, 24 Sep. 1764. BL Add Mss 4444.

"From early in the century. Fellows of the Royal Society had
been making visits to the Royal Observatory, but not until Maskelyne
became astronomer royal in 1765 was the council designated as the
visitors. II. S. John w rote to the president of the Royal Society on 12
Dec. 1710 that it would benefit astronomy and navigation if the Royal
Society's "visitors" were to inspect the instruments of the Royal
Observatory, direct the astronomer royal to make observations they
thought proper, and require that the astronomer royal turn over his
observations each year. This letter was attached to the "Regulations
for the Astronomical Observer at Greenwich," of 1756. From
Maskclyne's speech about Bradley's observations, made to the Society
on 9 June 1763, Lord Charles Cavendish concluded that the council
members were "not really visitors of the royal Astronomer; but upon
Mr. Maskelynes being appointed to that office, they were made so."
Lord Charles Cavendish to Joseph Banks, 19 May 1781, Greenwich
Observatory Letters and Papers," Royal Society, vol. 2. Oh. 121.

Copyrighted malarial

Public Activites

visitations to Greenwich to decide on the repairs
needed and to estimate the expense, and in this
capacity again, his son Henry- would follow in his
footsteps. As late as 1781, two years before his
death, Cavendish was still discharging the Royal
Society's obligations, reminding the president of
the Royal Society that the publication of the
Greenwich observations was long overdue. 7 "

Cavendish's private interest in books and
manuscripts had a public outlet in the Royal
Society, where he served as one of a committee of
three inspectors of the library to report on the
addition of the great Norfolk library of books and
manuscripts. Having fallen into a state of neglect,
the Society's library in general benefited from
bookish types like Cavendish and his fellow
inspector Thomas Birch. This valuable library was
the size of a very good private library, around 10,000
volumes, which was just the size of Henry
Cavendish's private library later in the century. 79

Elected during Sloane's presidency,
Cavendish served through Folkes's, Macclesfield's,
and Morton's. In 1768, while the council was
absorbed in preparations for a second transit of
Venus the next year, Morton died. Like Macclesfield
before him, Morton was an astronomer, thus, an
appropriate president under these circumstances.
The next president turned out to be the
antiquarian James West, who had been the
Society's treasurer for thirty-two years and was
currently a vice-president. West held the office for
only four years, but it was long enough for Henry
Cavendish to have formed a strong negative
opinion of his presidency.™ Ten days after Morton
died, Daniel Wray wrote to Lord Hardwickc,
F.R.S., that "Lord Charles is deaf to all our prayers;
and will not preside over us." 81 Wray may have
meant that Cavendish would not preside over
them as temporary president or he may have meant
as permanent president. Since Cavendish was used
to sitting in for absent presidents, the latter
meaning seems more likely. Cavendish was in his
early sixties and in good health and on the council.
If he would not be elected president, it was in the
first instance because he did not want to be.

Science

Lord Charles and Henry Cavendish's
scientific work was of a kind that involved them in
a great deal of measuring, weighing, and perfecting

of standards. In these activities they were working
in a direction that was increasingly prominent in
the physical sciences. No other reason is required,
but because of the Cavendishes' place in society,
we note the following connection. Weights, mea-
sures, and standards are the preserve of central
political authority in modern commercial society. 8 -
Within eighteenth-century science, in which exact-
ness of reasoning was increasingly equated with
quantitative reasoning, authority tended to be
conferred on persons who were adept at measuring,
weighing, calculating, and making mathematical
theory (and, in part, because of that connection,
rebellion against that direction of science was
commonplace as well). With evident awe, William
Henly, an early expert on electrical measuring
instruments, wrote to a colleague that he had heard
that Henry Cavendish had determined iron wire to
conduct electricity 400,000 times better than rain
water, adding: "I suppose this, is mathematically
demonstrated. " 83

That Lord Charles Cavendish's scientific
work belonged to the best, we know from knowl-
edgeable contemporaries, just as we know that it

'""Visitations of Greenwich Observatory-, 1763 to 1815," Royal
Society, Ms. 600, XIV.d.11. Cavendish to Banks. 19 May 1781.

n Andrew Coltec Dutarel to Thomas Birch, 13 Oct. 1763. Birch
Correspondence, BL Add Mss 4305. 4:57. The library at this time
was described by one of the Society's officials as unkempt but not
negligible: "At present the books weigh lc-.s than the filth that
covers them. I compute about 100(10 vol to whit the Norfolk 500
MSS ex 3000 printed. The Society Library about 6000 printed books
only." Kmanuel Mendes da Costa to William Borlase, 9 Julv 1763. K.
Da Costa Correspondence, BL Add Mss 28535, 2:150.

""Henry Cavendish's opinion is reported in Charles Blagdcn to
Joseph Banks, 22 Dec. 1783, original letter in l-'it/william Museum
Library, copy in BM(NH), D'l'C 3. 171-72. We return to this point in
the chapter dealing with 1 lenry Cavendish's politics.

"'Daniel Wray to Lord Hardwicke, 22 Oct. 1768. in George
Hardinge, Biographical Anecdotes of Daniel Wray (London. 1815), 137.
Next month. James West presided over them as president.

"-'Witold Kula, Measures and Men, trans R. S/reter (Princeton:
Princeton University Press, 1986), 18.

"'William Henly to John Canton, n.d.. Canton Papers, Royal
Society, Correspondence 2:86. What Henly heard was off by a factor
of 1000. The figure 400,000 corresponds roughly to the experimental
measurements Cavendish made on saturated salt solution in 1773. I lis
experiments on rain water gave much higher figures, as he reported
in his published paper on the electric torpedo in 1776: "Iron wire-
conducts about 400 million times better than rain or distilled water."
the Electrical Researches of the Honourable Henri Cavendish, F.K..S. . .,
ed. J. C. Maxwell (Cambridge, 1879; London: Frank Cass reprint,
1967). 195, 295. 359. Henly's observation that Cavendish's proof was
no doubt mathematical derives from this fact: no one but Cavendish
knew how to compare resistances experimentally, and he had not
published his method. The first instrument capable of comparing
resistances was the galvanometer, which was long in the future:
Cavendish's method was, in effect, to use his body as a galvano-
meter, as we discuss later.

Cavendish

PLATE I. Lord Charles Cavendish's Thermometers. The thermometer in Figure I shows the greatest degree of heat. It differs from ordinary
thermometers only in that the top of the stem is drawn into a capillary tube, which ends in a glass ball C. The cylinder at the bottom and part of
the stem are filled with mercury (dark part of the figure), showing the ordinary degree of heat. Above the mercury is spirit of wine (dotted part of
the figure), w hich also fills the ball C almost to the top of the capillary tube. W hen the mercury rises with temperature, some spirit of wine is
forced out of the capillary tube into the ball. When the mercury falls with a fall in temperature, a space at the top of the capillary tube is emptied of
spirit of w ine. A scale laid beside the capillary tube measures the empty length, w hich is proportional to the greatest degree of heat that has been
registered. Figure 1 is an alternativ e construction. Figure 3 shows a thermometer for giving the greatest degree of cold. Figure 4 shows how the
instrument can be made more compact, as w ould be desirable if it were to be sunk to the bottom of the sea or raised to the upper atmosphere by a
kite. " A Description of Some Thermometers for Particular I ses," Philosophical Transactions .50 ( 1 757): 300.

Public Activites

was only little known to them, as it is to us.
Cavendish's only publication was a paper on a
meteorological instrument in 1757, by which time he
had been working in science for thirty years.
Macclesfield, then president of the Society proposed
Cavendish as the Copley Medalist, a choice which
the council unanimously approved. In his address to
the Society on the occasion, Macclesfield said that
Lord Charles Cavendish was as conspicuous for "his
earnest desire to promote natural Knowledge, and
his Skill and abilities together with his continual
Study and endeavour to accomplish that his desire"
as he was for his "high Birth and eminent Station in
life." Because of Cavendish's "excess of Modesty"
and a seeming insensibility of "his own extraordinary
Merit," the Royal Society, and consequently the
public, had been deprived "of many important
discoveries as well as considerable improvements
made and contrived by his Lordship, in Several
Instruments and Machines necessary for trying
Experiments and deducing proper consequences
from the Same; and also of the results of various
useful and instructive Experiments that he has been
pleased to make in private, with that accuracy and
exactness which are peculiar to his Lordship, and
which few besides himself have a just right to boast
() f "84 Within their lofty phrasing, Macclesfield's
remarks contain an accurate observation. In that
age of aristocracy. Cavendish was, as Macclesfield
said, an "Ornament" to the Royal Society, and he
was an ornament too because he promoted natural
knowledge, the purpose of the Royal Society. What
Macclesfield called Cavendish's "modesty" could
with equal right be called his "confidence." Given
his rank and his competence, he did not need to
(any more than Macclesfield needed to) publish his
researches. It was enough that he made them
available to his colleagues in the Royal Society. As
Macclesfield said, Cavendish had not kept his
work entirely to himself (otherwise how should
Macclesfield know) and had communicated papers
to the Royal Society not intended for publication.
With greater ease than those who had to advance
themselves in the world, Cavendish could live an
approximation to the cooperative scientific life
envisioned by the Utopians of the previous century.

We know that Cavendish did good work in
science because he was constantly in demand at
the Royal Society, certain to be appointed to
committees in which scientific skill, knowledge,

and exactitude were prized. His first scientific
committee was concerned with longitude at sea.
For over twenty years, the Board of Longitude had
been unimpressed until the watchmaker John
Harrison caught their attention. In principle, a
well-known alternative to the lunar method of
finding longitude at sea was a clock that is
seaworthy and accurate. Harrison, at first with his
brother, James, built a series of clocks and was
granted several sums of money by the Board of
Longitude as encouragement. The Royal Society
reported favorably on an early clock in 1735, and in
1741 Cavendish was one of twelve Fellows of the
Royal Society who recommended a perfected
version of his second clock to the Board of
Longitude as reason to continue to reward him. His
first clock overcame the disturbing variations of
heat and cold, moisture and dryness, friction, and
fluidity of oil so perfectly that its error was less than
one second a month for ten years running. This
wonder was, however, a delicate pendulum clock.
Harrison's second clock, built for shipboard, had
kept good time under all kinds of violent motions
simulating storms. Now Harrison planned a third,
even better machine. What is of interest here are
the persons Cavendish came together with on
the committee, Fellows selected, in most cases,
for their authority in matters of high precision.
The other eleven members were mathematicians,
astronomers, and instrument-makers: mathematicians
De Moivre and his circle, Folkes, Jones, Macclesfield;
astronomers Bradley and Halley; instrument-
makers John Hadley and George Graham; the
polymath James Jurin; and the Cambridge pro-
fessors Robert Smith and John Colson. The Board
of Longitude encouraged Harrison to continue to
improve his clock but withheld the crowning glory.
On the eve of a second trial run of Harrison's latest
clock to the West Indies, in 1763 Cavendish was
appointed by an act of parliament to another
committee on the subject. From what became a
lifework and legal battle, and with the help of
Cavendish and other Fellows of the Royal Society,
in the end Harrison got most of the money he
deserved and along the way a Copley Medal, and

'"The Copley Medal was awarded to Lord Charles Cavendish
"on account of his very curious and useful invention of making
Thermometers shewing respectively the greatest degrees of heat and
cold during the absence of the observer." Royal Society JB
23:638-48. quotations on 638-39 (30 Nov. 1757).

100

British ships got a reliable instrument for deter-
mining longitude. Captain (look used Harrison's
clock on his voyage to the South Seas in 1772,
justifying all the claims of precision made for it. 85

Lord Charles Cavendish's next assignment
two years later, in 1743, was again concerned with
measurement. The object this time was to compare
the Royal Society's weights and measures with
those kept by the Academy of Sciences in Paris:
measurements were becoming decisive in experi-
mental work, and depending upon the country
in which the work was done, measurements
were expressed in the Knglish foot or the Paris
toise, lengths marked off on metal standards and
deposited in various archives. Their comparison
was an obligation of the London Society and the
Paris Academy. The project expanded to include a
comparison of the Royal Society's standards with
other standards in Kngland, with the original
standards for the yard and the pound at the
exchequer and as well with other copies located at
various places in London. The instrument-maker
Cieorge Graham carried out the experiments in the
presence of a delegation from the Royal Society,
which, other than being smaller, was almost the
same as the committee that had investigated
Harrison's clock. Of the delegation of seven, five
we have discussed in connection with I)e Moivre:
Koikes, who was president then, Macclesfield,
Jones, Peter Davall, and Cav endish. The other two
were the instrument-maker I ladley and the
secretary Cromwell Mortimer. Cavendish was in
his element, that of precision and accuracy. 86

For our last example of Lord Charles
Cavendish's scientific work in committee, we turn
to his experiments on the compressibility of water.
The originator of the experiments was John
Canton, a schoolmaster best known for his experi-
ments in electricity, for which he had earned a
Copley Medal. His new experiments were highly
exacting, and the interpretation he put on them
contradicted a famous finding of the Florentine
Accademia del Cimento a hundred years before.
There arose, in a sense, a dispute between
scientific societies, even if one was defunct; the
honor of the Royal Society w as at stake.

Canton's apparatus was transparently simple:
a small, narrow glass tube was open at one end and
closed at the other by a hollow glass ball an inch
and a quarter across. The ball was placed in a water

Cavendish

bath, and it and a few inches of the tube were filled
with mercury. The bath was heated until the
mercury rose to the top of the tube, then the tube
was hermetically sealed. After the mercury had
cooled to its original temperature, Canton observed
that it stood about a half inch higher than before;
he found the same when water was used instead of
mercury, though the water rose slightly higher than
the mercury. The only difference before and after
the expansion of the liquid was the pressure of
the atmosphere over it. Water, Canton concluded,
is compressible. He published his experiments in
the Philosophical Transactions in 1762, and two
years later he published a sequel extending his
experiments to other liquids. In the sequel
Canton also reported his discovery of another
"remarkable property" of water: its compress-
ibility is less at summer temperatures than in
winter, contrary to his expectation and to the
behavior of other liquids. 87

Doubts were raised about the accuracy of
Canton's experiments and about his inference from
them about the compressibility of water. The
Monthly Rczieic\ which was not a scientific journal
but which nevertheless reviewed critically the
contents of the Philosophical Transactions, found

" v rhe act of 1763 altered the original act of 1714 offering the
prize. The other members of the new committee were Lord Morton.
Lord Willoughby, George Lewis Scott. James Short, John Michcll,
Alexander Gumming, Thomas Mudge, William Frodsham, and James
Green. Only the instrument-maker Short and the watch-makers
Frodsham and Green were satisfied with Harrison's explanation.
Cavendish was also appointed by the Board to another committee; John
Bird deptiti/ed for him this time. Taylor, Mathematical Practitioners of
Hanoverian England, 126, 170, 172. "Some Account of Mr. Harrison's
Invention for Determining the Longitude at Sea, and for Correcting
the Charts of the Coasts. Delivered to the Commissioners of the
Longitude, January 16th 1741-2," given in/John Harrison/, An Account
of the Proceedings, in Order to the Discovery of the Longitude (London,
1763), 7-8. 19, 21. Humphry Quill, John Harrison: The Man Who hound
Longitude (London: Baker. 1966), 12(1-22, 139-46, 186, 221.

w '"An Account of the Proportions of the Knglish and French
Measures and Weights, from the Standards of the Same. Kept at the
Royal Society." PT 42 (1742): 185-88. "An Account of a Comparison
Lately Made by Some Gentlemen of the Royal Society, of the
Standard of a Yard, and the Several Weights Lately Made for Their
Use; with the Original Standards of Measures and Weights in the
Exchequer, and Some Others Kept for Public I'se. at Guild-hull.
Founders-hall, the Tower, etc.," /'7'42 (1742): 541- 56. Select Tracts
and table Hooks Relating to English Weights and Measures ( 1 100-1742),
ed. II. Hall and F. T. J. Nicholas, Camden Miscellany, vol. 15
(London: Office of the Society, 1929), 40.

"'John Canton. "Experiments to Prove that Water is not
Incompressible." PT 52 (1762): 640—1.?; "Experiments and
Observations on the Compressibility of Water and Some Other
Fluids," /•'/' 54 (1764): 261-62. John Canton to Benjamin Franklin,
29 June 1764. in ////• Papers of Benjamin Franklin, vol. 11. ed. L. W.
Labaree (New Haven: Yale University Press. 1959), 244 — 16, on 245.

Public Aaivites

fault with the experiments in both of Canton's
papers. The critic for the journal concluded that
Canton's experiments would ultimately be judged
as inconclusive as the Florentine they claimed to
disprove. By the time the Monthly Review com-
mented on Canton's second paper, the Royal
Society had honored Canton with the Copley
Medal; the journal hinted that this award was to
the Society's dishonor. 88

The question of awarding a second Copley
Medal to Canton for his experiments on the
compressibility of water was moved in council, but
in "conversation" some Fellows of the Royal
Society expressed objections. Concerned for the
"honor of the Society," on 28 November 1764, the
council appointed a committee to repeat Canton's
experiments at the expense of the Society and to
report back to the council. 89 The president was
directed to inform the Society that any objections
to Canton's experiments had to be submitted in
writing if they were to be considered by the
committee. On 17 June 1765 the council ordered the
instruments by the committee,'" 1 and the committee
selected the instrument-makers John Bird, James
Ferguson, and Fdward Nairne to assist it in carry ing
out the experiments. 41 It was summer, the Society
was in recess, and many of the committee members
were out of town. Those who remained — Lord
Charles Cavendish, Franklin, Watson, Heberden,
and Ellicott — met four times in July to perform
experiments in the Musem of the Society. At the
beginning of August the clerk of the Society, Emanuel
Mendez da Costa, informed the president, Lord
Morton, that the attending members of the Com-
mittee were convinced of Canton's conclusion, but
since they were "all friends to the experiments,"
da Costa anticipated a "contest," especially since
the experiments were of such "nicety." 92 In
November, after the Society had resumed its
meetings, some of the experiments were performed a
second time before the larger committee.

This larger committee contained the princi-
pal skeptic of Cantons claims, Francis Blake, an
Oxford mathematician who was an active, highly
regarded member of the Society. Blake raised this
and that question about Canton's experiments, but
his essential concern appears to have rested on an
appeal to authority backed up by what seemed to
him commonsense. In the Florentine experiment,
water was subjected to great pressure without,

101

evidently, causing any change in its bulk, whereas
in Canton's experiment, an observable change was
alleged to have resulted from a very slight pressure.
Which account was Blake to credit? As requested,
Blake put his question to the council in writing. 93

Cavendish was a friend of Canton, and
since his repetition of Canton's experiments was
not private but judicial, he kept Canton well
informed. He sent Canton his measures and
computation to review. Everything was above
board: throughout Cavendish wrote "by my
measure," and he signed the bottom of every
sheet. We have Canton's ordeal to thank for the
only surviving record of Cavendish's experimental
work, preserved in Canton's papers. The impression
this work gives is one of great thoroughness and
accuracy, characteristics that apply equally to the work
of his son Henry, of which we have ample record. 94

In a paper drawn up for the council.
Cavendish stated and answered the objections to
Canton's experiments that had come to his
notice. 95 The first objection went to the heart of
the matter, the conflict with the Florentine
experiment. Experiment is authority, Cavendish
said, in effect, and experiment can overrule
experiment. In response to Blake's objections.
Cavendish wrote a separate paper in response to

*TAt Monthly Reviev 29 (1763): 142-44. and 33 (1765): 455-56,
quotation on 456.

"''Besides Cav endish, the committee consisted of the president,
Matthew Raper, John Ellicott, James Short. William Watson, Israel
Maudit, and Charles Morton. 28 Nov. 1764, Royal Society, Minutes
of Council 5:57. Francis Blake, Edward Delaval, Benjamin Franklin,
and Ceorge Lewis Scott were added to the committee: 21 Feb. 1765,
ibid.. 62-63.'°Royal Society, Minutes of Council 5:57 (28 Nov. 1764),
and 109(17 June 1765).

'"John Bird is referred to in Cavendish's memoranda on the experi-
ments. James Ferguson was paid for his time and trouble: 10 July 1766,
Royal Society, Minutes of Council 5:161. Edward Nairne was also ap-
pointed according to Lord Morton: 30 Nov. 1765, Royal Society. JB 25:655.

92 EmanucI Mendez da Costa to the earl of Morton. 1 Aug. 1765,
in John Nichols, Illustrations of the Literary History of the Eighteenth
Century, 8 vols. (London. 1817-58) 4:754.

'"Blake was the only doubter to give the council anything in
writing, and his paper was mislaid and came to the attention of the
committee late in its deliberations. Francis Blake. "Remarks and
Queries Recommended to the Consideration of the Right Honourable
the Karl of Morton," Canton Papers, Royal Society, 3.

<M Thc sheets in Cavendish's hand record his variations on
Canton's experiments and include sketches of his apparatus. They
give numbers for trials with glass balls of different sizes and
thicknesses and a large number of glass tubes, and they give a table
of the expansion of water with heat, from thirty degrees to fifty.
Canton Papers. Royal Society. 2.

'''Ibid. These objections are contained also in another, much
longer (eleven-page) paper, which would also seem to have been
written by Cavendish, though the copy in the Canton Papers is not
in his handwriting.

Cavendish

Blake's objections, which he began by making the
same point: "The authority of the most able
experimenters /including the Florentine/ is of no
weight, when it appears that their experiments
were made in such a way, as could not possibly
show so small a degree of compressibility as Mr
Canton has discovered. " % There had been progress
in the art of experiment in the century since the
Florentines; Canton's skill in showing "so small a
degree of compressibility" was proof of that, as was,
in its way, Cavendish's follow-up. On 28 November
1765 the council resolved that the hypothesis of
the compressibility of water accounts for Canton's
experiments and that no other appears to do so as
satisfactorily, and it voted to award Canton the
Copley Medal for 1764.'' 7 Two days later, at a general
meeting of the Society, Lord Morton presented the
Medal to Canton and gave an address, in which he
brought up the controversy. He did not describe the
ensuing experiments carried out at the Society,
since Cavendish had written a "full and accurate
Account" of them and of the "Theory deducible
from them.'"' 8 Cavendish's paper was read at the
next general meeting of the Society "

As the historian of the Royal Society Charles
Richard Weld put it. Lord Charles Cavendish had
given the Society a "warm and able" defense of
Canton's exquisitely precise experiment. 100 In his
address on the Copley Medal, Lord Morton referred
to the extraordinary work on Canton's experiments
by that "Noble Member of the Society," Lord
Charles Cavendish, w ho was "eminent for his great
Abilities, and deep knowledge in all the branches of
science that come before them." 101

"It were to be wished, that this noble philosopher
would communicate more of his experiments to the
world, as he makes many, and with great accuracy."
This reference to Charles Cavendish is contained in
a letter written in 1762 by one who knew, the able-
electrical experimenter Benjamin Franklin. 102 The
occasion was Franklin's admiration for Cavendish's
experiment on the conduction of electricity by
heated glass. From this source and from several
others, we know that Cavendish had a keen interest
in electrical conduction. This new subject had been
expanded by the discovery of the Leyden jar, or
electrical capacitor, an instrument which delivered
far greater quantities of electricity than did the
unaided electrical machine. The insulating and con-

ducting properties of glass had acquired particular
interest because of the behavior of the glass in the
Leyden jar. Franklin had shown that the whole-
power of the Leyden jar is concentrated in the
glass of the jar and not in the metallic foil coating
it. Cavendish's apparatus consisted of a glass tube
thickened to solid glass in the middle. It was, in ef-
fect, an ingenious Leyden jar, which he showed
ceased to work like a Leyden jar when the solid,
middle section of the glass was heated to 400 degrees
or higher; the evident reason was that the glass at
that heat ceased to be an insulator, as at lower
temperatures it must be for a Leyden jar made of
glass to work at all.

The man who best knew Cavendish's elec-
trical work was William Watson, the leading electrical
researcher in London. In 1747 Watson invited the
Royal Society to join him in an experiment on elec-
trical conduction, the scale of which, miles literally,
was a measure of his enthusiasm for the subject.
This inspired experiment was made possible by
the new Leyden jar, the discharge, or "explosion,"
of which could communicate shocks over long di-
stances. Nobody knew how long; Watson thought that
a powerful Leyden jar might send a shock clear
across the River Thames. To try that idea (Watson
must have had a good idea that it would work),
Watson and "many others" assembled at the new-
Westminster Bridge (to which Cavendish had
recently devoted so much work). A wire connected
to a Leyden jar was laid across the bridge, and with
the river and the bodies of the experimenters
completing the circuit, Watson and his associates

'"•Lord Charles Cavendish, "Observations on Mr Blake's
Objections to Mr Canton's Experiments," Canton Papers. Roval
Society, 3.

" ; Royal Society. Minutes of Council 5:141— +2 (21 and 28 Nov. 1765).

'"Lord Morton's address was given at the anniversary meeting,
30 Nov. 1765, Royal Society, JB 25:647-64. Quotation on 656. The
award of the Copley Medal to Canton for his experiments on the
compressibility of water did not bring the work of the committee to
an end. Two and a half weeks later the council resolved that an
experiment on the compressibility of water proposed by Lord Morton
be resumed. 19 Dee. 1765, Minutes of Council. Royal Society, 5:148.

'"Two papers by ( )a\ endish. one an appendix to the other, were read:
"A Paper Delivered to Mr. da Costa for the Use of the Committee on
Mr. Canton's Kxperiments," dated 21 Oct. 1765, and "Appendix to
the Paper on Mr. Canton's Experiments," dated 5 Dee. 1765, Royal
Society, JB 25: 668-79. The material is also in the Canton Papers,
Royal Society, 3.

""'Weld. Royal .Society, 2:32.

""30 Nov. 1765, Royal Society. JB 25:656.

"'-Benjamin Franklin to Ebenezer Kinncrsley, 20 Feb. 1762, in
The Papers of Benjamin Franklin, vol. 10. ed. L.W. Labaree (New
I laven: Yale University Press, 1966). 37-53. on 42.

Public Activites

103

felt shocks in their wrists and elbows when the jar
was discharged. The circuit was progressively
lengthened until finally the experimenters moved
from the river onto dry land, at Shooters' Hill.
Using signals and watches in an attempt to
quantify electrical conduction, they were forced to
conclude that conduction is "nearly instantaneous."
In these experiments, which went on for weeks,
twenty-five Fellows of the Royal Society took part,
Charles Cavendish, needless to say, one of them.
Almost all the rest of the De Moivre circle was
there too: Folkes, Stanhope, Davall, Jones, and Scott.
Bradley was there, as were most of the leading
instrument-makers. These outdoor experiments in
the middle of summer were an outing as well as an
enquiry into nature; Stanhope, for one, brought
venison pastry and French wine."" The experiments
were financed by and "made by the order and for
the service of the /Royal/ Society," 104 and Watson
published an account of them in the Philosophical
Transactions.^ Of the phenomena produced by the
equipment of the experimental philosopher,
nothing could compare with Watson's experiment
on the Thames for drama. In nature the only
comparable phenomenon studied by the
philosopher was lightning, which was understood
to be a phenomenon of the same kind. Electricity
was clearly the next great natural power to be
subjected to the rule of law. We suspect that that is
how Lord Charles Cavendish saw it, and we know
it was the way his son Henry did.

Lord Charles continued to assist Watson in
his researches on electricity. In a paper in 1752
Watson published an apparatus made by Cavendish
for the conduction of electricity through a vacuum.
Watson passed electricity from a machine and from
a Leyden jar through a vacuum to learn if the
vacuum transmits electricity; he found that it does,
though not as freely as do metals and water. He
had to make do with the imperfect vacuum
obtained by an air pump until Cavendish solved
the problem with an apparatus that achieved a
Torricellian vacuum and an electrical circuit at
once. Bending a narrow glass tube seven and a half
feet long into a parabolic shape, Cavendish filled
the tube with mercury and placed its ends in basins
of mercury; the mercury in the two arms of the
parabola descended until the level stood about
thirty inches above the basins, leaving a Toricellian
vacuum at the top of the tube. Cavendish brought

up a wire from an electrical machine, which caused
electricity to pass through the vacuum in a "con-
tinued arch of lambent flame." The simplicity and
ingenuity of Cavendish's apparatus are again striking
to us, as they were to Watson. Cavendish, Watson
observed, joined a "very complete knowledge" of
science with that of making apparatus. 11 "'

Of Lord Charles Cavendish's apparatus, the
ultimate in simplicity was his sealed vessel for
converting water to vapor, though all we have to go
on his son Henry's admiring references to it." 17
From Henry, we also know that Lord Charles did
experiments on the bulk of water over a very wide
range of temperatures, 10 " that he determined the
expansion of steam with heat," w that he did experi-
ments on the depression of mercury in glass tubes
of different sizes, 110 that he determined the expansion
of mercury with heat, 111 that he did chemical
experiments, 112 and that he made astronomical
observations together with Henry." 3 He computed

""Thomas Birch to Philip Vorkc, 15 Aug. 1747, BL Add Mss
35397, ff. 70-71 1747, BL Add Mss 35397, ff. 70-71.

""Royal Society, Minutes of Council 4:15 (17 Oct. 174X).

l05 William Watson. "A Collection of the Electrical Experiments
Communicated to the Royal Society." PT45 (1748): 49-120.

""■William Watson, "An Account of the Phaenomnena of
Electricity in Vacuo, with Some Observations Thereupon," PI 47
(1752): 362-76, on 370-71.

""Henry Cavendish mentioned his father's experiment to
various persons; e.g., to the instrument-maker Edward Nairne in
1776 for its bearing on the effect of moisture in an air pump, as
reported by John Robison, A System of Mechanical Philosophy, ed. I).
Brewster, 4 vols. (Edinburgh, 1X22) 3:593.

" w In connection with government taxes on spirits, Henry
Cavendish supplied a table of the bulk of water at degrees of heat
from 25 to 210 degrees. "From the Experiments of Lord Charles
Cavendish, Communicated by Mr. Henry Cavendish. March 1790,"
Blagden Collection, Royal Society, Misc. Notes. In the same
connection, Henry Cavendish communicated the weight of a cubic
foot of water, "the result of my father's experiment." I lenry
Cavendish to Charles Blagden, undated /probably 1790/, Royal Society.

""Thomas Voting, A Course of Lectures on Saturn! Philosophy nntl
the Mechanical Arts, vol. 2 (London, 1807), 401.

""Henry Cavendish included his father's tabic of the depression
of mercury in his report on the meteorological instruments of the Royal
Society in 1776: "An Account of the Meteorological Instruments
Used at the Royal Society's House," PT66 (1776): 375-401; in .Sri.
Ptip. 2:112-26, on 116.

'"Young, Natural Philosophy, 2:391.

11 : l lere and there I lenry ( lavendish referred to his father's chemi-
cals; e.g., 16 June 1781, "Experiments on Air," Cavendish Mss II, 5:56.

"'Packet of astronomical observations from 1774, in Lord
Charles Cavendish's hand, with Henry Cavendish's observations
interleaved, and kept by Henry in his own papers. Cavendish Mss,
Misc. We know of Lord Charles Cavendish's interest in astronomy
from sources other than his son, too; e.g., William Ponsonby,
Viscount Duncannon to the duke of Devonshire. 24 Jan. 1744/43,
Devon. Coll.: "I have not had an opportunity lately of seeing Lord
Charles, but I make no doubt of his Lordship having made proper
observations on the Comet, which appears here in great Splendor."

104

Cavendish

tables of errors of time for William Ludlam, an
astronomer at Cambridge and unsuccessful candidate
tor the Lucasian professorship of mathematics. 114
I le made meteorological observations with
Heberden, " s and he kept a meteorological journal,
as we know from the correspondence of William
Borlase. 116 But in the end, we have only a scanty and
fragmentary record of Lord Charles Cavendish's
experiments and observations. We know little more
than that he made many and that his contemporaries
knew of them and were impressed.

We conclude our discussion of Lord Charles
Cavendish's public activities with his membership
in a new society that, it would seem, more than any
other body breathed the spirit of the times.
Founded in 1754, the Royal Society of Arts enlisted
in the cause of human progress, calling upon the
ingenuity of the race to advance it. The hopeful
application of empirical knowledge was to be
stimulated by competition; persons with winning
ideas for improvements were to be awarded prizes
from money donated by public-spirited supporters
of progress. Given its ambition, the Society
predictably attracted a good many fellows of the
Royal Society, such as f ranklin. Knight, Macclesfield,
I leberden, and Watson. The latter proposed Lord
Charles Cavendish, who was elected on H June
1757. Because the Society also attracted a strong
aristocratic patronage, Cavendish found himself at
home in it in another way. Its list of members
included the dukes of Devonshire and Bedford,
the earls of Besborough and Ashburnham, Viscount
Royston, and Lord George Cav endish, members all
of the Cavendish clan as well. It is indicative of
Lord Charles's breadth of public interests that in
1760 he was appointed to special committees for
judging competitions in the fine arts, industrial
technology, and agriculture. 1 17

In what follows, part 3 of this biography and
beyond, our focus shifts from Lord Charles, a well-
rounded representativ e of his age, to his son Henry,
for whom we lack any such ready characterization.
A child of the English Enlightenment Henry

Cavendish certainly was, but we would hesitate to
call him one of its models, and yet neither would
we comfortably apply to him our own designation
scientist. Let us, then, get to know (more or less)
without preconceptions this wizard, as he was
known by his neighbors, a man who spoke rarely
and when he did with tremendous difficulty and
hesitation and into the void, who fought off any
attempt to draw him into conversation, reacting in
horror to a strange face, averting his eyes from the
gaze of others, walking alw ays dow n the middle of
the road acknowledging no passersby, acting ever
nervous, and caring nothing of how he appeared to
the world. No less striking than these singularities
was his self-assurance, his absolute confidence in
his chosen path. He knew what mattered to him,
science, and he pursued it with a singleminded will,
relentlessly, as we will see. We should be surprised
if at least some of our readers do not respond with
wonder, as we do, and as his contemporaries did, to
Henry Cavendish's forbidding integrity, strange
dignity, and manifest genius.

ll4 Lord Charles Cavendish. "Difference to Be Subtracted from
Sidereal Time to Reduce It to Mean Time." This and two other
tables of calculations on errors of time, in William Ludlam.
Astronomical Observations Mack in St. John's College, Cambridge, in the
Years 1767 and 1 76S: With an Account of Several Astronomical Instruments
(Cambridge. 1769). 145— IK. Thomas Baker. History of the College of St.
John the Evangelist. Cambridge (Cambridge, 1H69), 1069-70.

1,s In 1769 Lord Charles Cavendish's good friend, the physician
William Heberden published a paper in the Philosophical Transactions
comparing the rainfall at the bottom of a tall building with that at the
top. Benjamin Franklin had an explanation, which he put in a letter
and in which he referred to the experiments of Heberden and Lord
Charles Cavendish, both "very accurate experimenters." Franklin to
Thomas Percival, undated /probably June 1771/, in The Papers of
Benjamin Franklin, vol. W. ed. W. B. Willcox (New Haven: Yale
University Press, 1974). 15.S-.S7, on 156.

'"'Letters from William Borlase to Thomas I lornsby in 1766 and
to Charles Lyttleton in 1767, quoted in J. Oliver, "William Borlase 's
Contributions to Eighteenth-Century Meteorology and Climatology,"
Annals of Science 25 (1969): 275-31 7, on 293.

ll7 Kntries for 26 Mar.. 9 and 30 Apr. 1760. "Minutes of the
Society," Royal Society of Arts. veil. 5. Derek Hudson and Kenneth
W. Luckhurst, The Royal Society of Arts 1754-IV54 (London: John
Murray, 1954), 6. There was a considerable overlap in the member-
ship cjf the Society of Arts and that of the Royal Society: of the
eleven founding members of the Society in 1754. four w ere Fellows
of the Royal Society, and in 176S the president and all of the ten
v ice-presidents of the Society were F ellow s of the Royal Societv.

Copyrighted material

PART 3

The Honourable Henry and
Lord Charles Cavendish

CHAPTER 1

Education of Henry Cavendish

Hackney Academy

Henry Cavendish no doubt received an early
education from tutors. We know that one of his first
cousins had a tutor who was paid one hundred
pounds a year, 1 and we assume that a comparable
investment was made in Henry's early education.
Given that education limited to tutoring at home
had disappeared in England by the early eighteenth
century, Lord Charles had to make further arrange-
ments; he had the choice of sending his sons,
Henry and Frederick, either to a public school or to
a private one. Lord Charles had been to a public-
school, and he might have been expected to educate
his sons in one too, especially since that was in-
creasingly the practice among the aristocracy. Public-
schools, the argument went, were the proper training
ground for public lives, the destiny of the upper
classes. Most of the English peerage, for example,
were educated at Eton and Westminster, which gained
a reputation as nurseries of statesmen. 2 Cavendish's
sons may not have looked to him like statesmen; in
any case, he chose to send them to a private school.

Cavendish had his pick of convenient
private schools, since most of them were located in
the suburbs of London.' There was a variety of types
to choose from: certain schools were denominational,
others were classical, others neither. The one
selected by Lord Charles Cavendish was one of the
so-called academies, which offered a modern
curriculum that emphasized mathematics, natural
sciences, vocational subjects, and the most important
modern foreign language, French. Academies also
taught the ancient languages for their educational
value while de-emphasizing rote learning (their
students' Latin being the less proficient for it). With
an enrollment of about one hundred, Hackney
Academy was the largest of these academies, and it
was also the oldest, founded in 1685, and the most
fashionable academy in eighteenth-century England.
There Lord Charles Cavendish chose to educate
his sons, first Henry and then Frederick. 4

The Academy was located two miles
northeast of London, in the village of Hackney,
which at mid century numbered a thousand or so
householders. The inhabitants included a few
craftsmen, such as the well-known mathematical
instrument-maker John Ellicott, who with Peter
Holland observed the transit of Venus there in
1761;. 5 but the village was best known for the rich
Londoners who built country seats there. The
traffic between London and Hackney was so heavy
that "hackney" had become the general word for
coaches of the type that plied the route. Hackney
Academy, with its magnificent playing fields and
clean air, enjoyed a reputation for healthy living/'
Like other private schools, it was also thought to
answer the standard complaint about the public-
schools, their rampant sexuality. Hackney, in sum,
was modern, healthy, and safe.

Hackney attracted a certain kind of clientele.
Whereas many academies took in day students
from the lower middle class or the crafts, Hackney
was strictly a boarding school for the upper middle

'Henry Cavendish's aunt Rachel Cavendish married Sir William
Morgan of Trcdgar: they had two sons, William and I'd ward, born a
few years before Henry Cavendish, and one of these "Master
Morgans" had a tutor who received one hundred pounds per annum.
This is according to Lord Charles Cavendish in an account for his
widowed sister, undated /1 740/, Devon. Coll., no. 167.1.

-'Of the peers about the same age as Lord Charles Cavendish, 46
attended Eton and 31 Westminster; of those about the age of Henry
Cavendish, 53 attended Eton and 78 Westminster. From the count in
John Cannon, Aristocratic Century: The Peerage of Eighteenth-Century
England (Cambridge: Cambridge University Press, 1984), 40, 43-44.

'Randolph Trumbach, The Rise of the Egalitarian Family... (New
York: Academic Press. 1978), 254, 265.

4 Nicholas 1 lans, Xrw Trends in Education in the Eighteenth Century
(London: Routledgc & Kegan Paul, 1951), 63-66, 70.

S E. G. R. Taylor, The Mathematical Practitioners of Hanoverian
England, 1114-1840 (Cambridge: Cambridge University Press,
1966), 156.

'William Thornton, New, Complete, and Universal History,
Description, and Survey of the Cities of London and Westminster. . .
Likewise the Towns, Villages, Palaces, Seats, and Country, to the Extent of
Above Twenty Miles Round, rev. cd. (London, 1784), 481. Daniel
Lysons, Environs of London; firing an Historical Account of the 'towns,
Villages, and Hamlets, Within Twelve Miles of That Capital, vol. Z: County
of Middlesex (London, 1 795), 450-51 .

108

Cavendish

and upper classes, in particular, for wealthy whig
families. The hard-headed Lord Hardvvicke had
sent his son Philip Yorke to Hackney to get a good
modern education ten years before Lord Charles
Cavendish sent his son Henry. The duke of
Grafton, the earl of Essex, and the earl of Grey,
whigs all, patronized Hackney. So did the duke of
Devonshire, who sent his son Lord John Cavendish
there at the same time that his brother Lord
Charles sent Henry. Lord John and Henry were
evidently the first Cavendishes to attend Hackney,
soon to be joined by Henrys brother, Frederick.
They in turn were followed by the sons of the next,
the fourth, duke of Devonshire, Lord Richard and
Lord George Henry Cav endish. Hackney became
a Cavendish tradition. 7

For most of the eighteenth century, Hackney
was run by the Newcomes, a family of teachers,
Anglican clergy, and Cambridge graduates with an
interest in science. So identified with the school
was the family that Birch referred to it as "New-
come's Hackney." The first of the Newcomes,
Henry, who was said to be a good classical scholar
and strict disciplinarian, was still headmaster when
Henry Cavendish was there. There was a close
connection between the Newcome family and
Lord Charles Cavendish's own. Henry Newcome
and his son Peter Newcome, who later became
headmaster himself, were friends of the duke of
Kent's family and dined with them at St. James
Square/ Lord Charles Cavendish had a high
opinion of Peter Newcome. In 1742, just as he
entered his son Henry at Hackney, Lord Charles
recommended Peter Newcome for membership in
the Royal Society, identifying him as one who was
well skilled in mathematics and polite literature.
Co-signers of the certificate included the Hackney
graduate Yorke, Birch, and VVray, strongly suggesting
that Peter Newcome was one of Cavendish's
circle. 1 ' Birch, VVray, and Yorke often visited the
Newcomes at 1 laekney, and they went regularly to
the Hackney Theater, where Shakespearean plays,
for which the school was famous, were put on by
the students even,' third spring." 1 While Henry
Cavendish was at Hackney, Newcome joined Lord
Charles Cavendish and others in participating in
Watson's experiments on the conduction of elec-
tricity across the Thames, and a year after Henry
had left Hackney, Newcome published his observa-
tions on an earthquake felt at Hackney in the

Philosophical Transactions. ." Shortly before Henry
Cavendish was elected to the Royal Society, Peter
Newcome invited him to a meeting as his guest. 12
In 1763 and 1764 Newcome was a member of the
council of the Royal Society." We find clear
connections between Lord Charles Cavendish's
scientific interest and Hackney.

Students were admitted to Hackney at age
seven, but Henry Cavendish did not enter until he-
was eleven, in 1742. The six-year advanced course
that he took contained subjects that would apply to
his later studies and work, mathematics, natural
sciences, French, and Latin. In 1749, at age seven-
teen, the usual leaving age for students going on to
the university, Henry Cavendish, like all of the other
Cavendishes and like most of the other students at
Hackney, proceeded directly to the university.

Peterhouse, Cambridge

From the fourteenth century to the time-
Henry Cavendish entered Cambridge, twenty
Cavendishes had graduated from this university. 14
The first of the dukes of Devonshire to get a
university education, however, was the third duke,
who went to Oxford not Cambridge, though he sent
his two sons to Cambridge. His only surviving
brother. Lord Charles, likewise sent his two sons to
Cambridge. The eldest, Henry, having just turned
eighteen, entered St. Peter's College, or Peterhouse,

7 Hans, New Trends. 72. 243-44.

" Thomas Birth Diary, BL Add Mss 447KC, frequent entries
beginning in 1 740.

''Royal Society. Certificates, vol 1. Nr. 12, f. 260 (25 Nov. 1742).
The other signers were Jurin, Benjamin Hoadley. John Ward, and
Thomas Walker. Newcome was elected on 24 Teh. 1743.

"'Birch Diary. After dining at the Mitre in the afternoon, Wray
and Lord Willoughby planned to go to the Hackney 'Theater, and
they asked Birch to join them. Daniel VVray to Thomas Birch, IS Apr.
1 74JS, BL Add Mss 4322, f. 111. There were other occasions too:
Newcome invited Birch to Christmas at Hackney, 24 Dec. 1744, BL
Add Mss 43 I S, f. 222.

"William Watson, "A Collection of the Electrical Experiments
Communicated to the Royal Society," PT 45 (174K): 49-120, on 62.
Newcome reported the earthquake as it was felt by persons at his
house in Hackney; these included the son of John Hadley, the great
instrument-maker and vice-president of the Royal Society. "A Letter
from Mr. Peter Newcome F.R.S. to the President, Concerning the
Same Shock Being Felt at Hackney, Near London," PT 46 (1750):
653-54; read 29 Mar. 1750.

'-Royal Society, JB 23: 711 (10 Jan. 1760).

' 'Royal Society. Minutes of Council, 5.

IJ John and J. A. Venn. Alumni Cantabrigjenses . . .. pt. 1: From the
Earliest 'limes to 1751. vol. 1 (Cambridge: Cambridge University
Press. 1954).

Copyrighted m aerial

Education of Henry Cavendish

109

Cambridge, on 24 November 1 749. 1 s He was the
first Cavendish to go to that particular Cambridge
college, where he remained in regular attendance
for over three years.

Henry Cavendish was never far from
evidences of family power. Two years before he
arrived at the university, Philip Yorke, a relative on
the Grey side, was elected to parliament from the
county of Cambridge. In the next election he and
John Manners, the marquess of Granby, a relative
on the Cavendish side, were returned unopposed.
These two Members of Parliament represented the
two aristocratic whig families of Hardwicke and
Rutland that vied for power in Cambridgeshire and
dominated its politics. 16 The chancellor of the
university was the duke of Newcastle, a whig, a
minister of state, and distantly related to Cavendish.
Newcastle did what was expected of him by
securing for the university a bountiful share of
crown livings, deaneries, and bishoprics. As it
happened, in the year that Newcastle became
chancellor, the master of Peterhouse died, and
Newcastle promptly appointed a whig in his place, a
fellow of Peterhouse, Edmund Keene. This was
Newcastle's way of rewarding Keene for his active
support of the whig interest in Cambridge. In
1750-51, while master of Peterhouse, Keene served
as vice-chancellor of the university, the most
important resident officer; usually the vice-
chancellor served for only one year, but Newcastle
got Keene to serve two years because he was so
compliant. Horace Walpole put it more bluntly:
Keene was "Newcastle's tool" in the university. As
another contemporary put it, Keene was a "very
sensible & agreeable man." 17 In any event, Keene
went on to still higher things, becoming Bishop of
Ely. While Keene was still at the university,
especially through his brother, the distinguished
diplomat Sir Benjamin, F.R.S., he was in touch
with the larger world, including men of science. 1 *

Lord Charles Cavendish helped see to that.
A close shepherd of his sons' education, he was on
familiar terms with Keene at Peterhouse, as he was
with the Newcomes at Hackney. While Henry
Cavendish was at Peterhouse, Keene dined with
Cavendish's friends. Birch, Heberden, Wray, Mann,
and Squire, and on one occasion Keene dined with
Birch and Cavendish. 1 '' Keene is said to have had a
preference for the privileged, and although Peter-
house was not a stronghold of the nobility, for a time

in the middle of the eighteenth century, it was
fashionable with the upper classes. 20 Evidence of this
is that the Cavendishes, Henry, Frederick, and their
cousin Lord John, and soon after them, a distant
relative James Lowther, all went to Peterhouse.

To a visitor entering Cambridge from the
direction of London, the first college on the left on
Trumpington Street was Peterhouse, the (then
disputed) oldest college in Cambridge, dating from
the thirteenth century. The buildings of the
college formed two courts separated by a cloister
and gallery. There was an impressive chapel with a
painted glass window depicting Christ's crucifixion
between two thieves; the most eminent alumni of
Peterhouse were bishops. 21 According to a
description from the time Cavendish was at
Peterhouse, the college then had forty-three
scholars and a total membership "of all Sorts" of
about ninety. 22 These figures, however, give an
exaggerated idea of the residential society of
Peterhouse and of the university. When the poet
Thomas Gray was a student at Peterhouse, not
long before Cavendish, there were not a dozen
undergraduates in residence at any given time, and
in the entire university there were only about four
hundred residential students and about an equal
number of fellows. 25

ls The date, recorded in the Peterhouse books, is given j n
George Wilson, 'The Life of the Honourable Henry Cavendish (London.
1851). 17.

"•The Victoria History of /he Counties of England. Cambridge and the
Isle of Ely (London: Dawsons of Pall Mali reprint, 1967) 2:412-1.?.

"Comers Middleton to Thomas Bireh, 16 Jan. 1748/4'*. BL Add
Mss 4314, f. 30.

'"Dcnys Arthur Winstanlcy, Vnreformed Cambridge (Cambridge:
Cambridge University Press, 1935), 13, 193. Horace Walpole, Harare
Walpole's Correspondence, cd. W. S. Lewis, 48 vols. (New Haven: Vale
University Press, 1937-83), vol. 2, pt. 4, p. 346. "Keene, Kdmund,"
D.VB 10:1191-92, on 1192. Keene, like the Hackney Newcomes, and
like Lord Charles Cavendish, subscribed to an important scientific
publication at this time, Colin Maclaurin, An Arrount of Sir Isaac
Xevfon's Philosophical Discoveries (London, 1748).

'''Birch Diary, 6 June 1747. 17 May 1751, 18 and 22 Feb. 1752.

-"Winstanlcy, Vnreformeel Cambridge, 193. Of peers born in
1711-40, Henry Cavendish's period, only three went to Peterhouse.
By contrast, nine went to Clare, eight to King's, seven to Trinity, and
six to St. John's. In attendance at Cambridge, in 1740-59. when
Henry Cavendish was there, out of twenty-seven peers' sons, only
three w ere at Peterhouse. Cannon, Aristocratic Century, 48-51.

Z M Concise and Accurate Description of the University, Tovn, and
County of Cambridge, new cd. (Cambridge, n.d. /probably 1784/), 16.
Joseph Wilson, Memorabilia Cantabrigiae: or, an Account of the Different
Colleges in Cambridge . . .(London. 1803), 1-3.

"Edmund Carter, The History of the University of Cambridge, from
Its Original, to the Year It '53 (London, 1753), 29.

2, Robert Wyndham Kctton-Crcmcr, 'Thomas Cray: A Biography
(Cambridge: Cambridge University Press, 1955). 10.

Cavendish

Although at the time Henry Cavendish
entered Cambridge, the overall attendanee at the
university was small and declining, the proportion
of students who were aristocratic- was rising.- 4
Peterhouse reflected the hierarchical character of
Knglish society. Its foundation consisted of a
master and fourteen fellows with an additional
eight bye-fellows on special foundations. The
master, who was elected from among the fourteen
fellows, was entitled to a sizable estate, with
considerable financial advantage and patronage,
and he had autocratic power. He lived in a lodge-
across the street, Trumpington, which drew a line
of demarcation between him and the other fellows.
There were a dozen other annually elected officers
in the college, who discharged their corporate
duties in hierarchical order: before a fellow could
become a lecturer, he had first to be a bursar, and
so forth. Peterhouse students were classed roughly
in accordance to their station in life: in ascending
order, they entered as sizars, pensioners, fellow-
commoners, or noblemen. Sizars, who were the
poorest and were charged the lowest fees, and who
were really a college charity, were sons of poor
clergy, small farmers, petty tradesmen, and artisans.
The majority of students were pensioners, who
were better off, commonly sons of more prosperous
clergy and professional men, but without
distinction of birth. Noblemen paid the highest
fees, and since they did not have substantial
privileges beyond those of fellow-commoners, they
often settled to be fellow-commoners.-' 1 ' In general,
the university reinforced the order of society; that
is, the political supremacy of the upper classes.- 6

Fellow-commoners were occasionally older
men who simply liked university life, but most of
them were young men of independent means,
often of considerable wealth and rank, scions of
nobility; country families, and commercial magnates.
They were conspicuous, often extravagant, inclining
to fine dress, sometimes appearing with their own
servants, and in any case able to afford to hire poor
students to wait on them. They were equivalent to
the fellows of the college in that they were
admitted to the fellows' table, common room, and
cellar, where they smoked clay pipes and drank
Spanish and French wine. Usually they were
excused from performing the college exercises
required of humbler undergraduates and of attend-
ing lectures by the college tutors.-' 7

When Cavendish arrived, Peterhouse had
twenty-four students, not all in residence, and
during his three and a half years there, fifty-nine
others were admitted. Of these, thirteen were
fellow-commoners, most of whom later went into
politics, with a sprinkling of nabobs and unclas-
sifTa hies; and of the others, sizars and, the majority,
pensioners, most became clerics. There were four-
teen Peterhouse wranglers, ranking third through
sixteenth, persons who did notably well on their
examinations, indicating competent tutoring in
mathematics. John Cuthbcrt and William Hirst
became Fellows of the Royal Society, and the lat-
ter, as a naval chaplain, assisted in observations of
the transits of Venus, 2 * but there is nothing in any
of this to suggest that this college might nurture a
great scientist.

The same might be said of Cambridge in
general. Thomas Cray described Cambridge fellows
as sleepy and drunken and fellow-commoners as
their imitators, and in his letters from Cambridge
he constantly referred to the stupor of the place.
There is a measure of truth in his observation, for
fellows of a college had little to occupy them
officially. They had given lectures at one time, but
by the middle of the eighteenth century their
teaching duties had largely fallen away, while their
fellowships were becoming sinecures. Most of
them took holy orders and waited in hope of
attaining a college living, freeing them to leave
Cambridge and to marry. While Cavendish was at
Cambridge, college lecturers still performed, but
the practice was on the way to extinction. The
motivation to do any work had to come from
within. While there were fellows who had a love of
learning and teaching, even a few who were great
scholars, most of them contributed nothing.' 1 '

The serious teaching that was done at
Cambridge was done by fellows who were also
tutors. Their job was enviable, entitling them to

-'■•Cannon, Aristocratic Century, 4.5.

"Thomas Alfred Walker, I'elerhotise (Cambridge: W Heffer.
1 935 ). 76-7H. ( :artcr. The History of the I 'nhxrsily of Cambridge, 5, 29.

-'•< lannon. Aristocratic Century, 34-35, 54—55.

- 7 \Vinstanlcv. Unrrformed Cambridge, 198. Walker, Peterhouse. 78.

-"Thomas Alfred Walker. Admissions to Peterhouse or S. Peters
College in the University of Cambridge, A Biographical Register
(Cambridge: Cambridge I Iniversity Press. 1912), 286-306.

-■'Winstanlev, I'nrrformed Cambridge, 256-61. Thomas Gray to
Horace Walpolc, 31 Oct. 1734, in Horace Walpole's Correspondence, vol.
13, pt. 1, pp. 58-59.

Copyrighted m aerial

Education of Henry Cavendish

111

fees from their students, and providing them with
hard-to-order stimulation. Lecturing regularly, and
ruling over their pupils as disciplinarians and
financial advisers, tutors could make and break the
reputation of a college. They had individual
influence, since their numbers were few at any
given time, only one or two in a college. 30
Peterhouse had two tutors, both formerly hard-
working sizars at the college, Charles Stuart and
Chapel Cox. Both had taken their M.A. seven years
before Henry came up and had tutored off and on
for the previous five years. 31 Both were vicars;
neither left a mark as a scholar or teacher. They
were everyone's tutor, and they tutored in
everything, and since no one in the college except
Cavendish took a scientific direction, we may
suppose that they were not strong in science. Lord
John Cavendish, Henry Cavendish's first cousin,
was also assigned to the same pair of tutors, though
he brought his own private tutor, and Henry might
have brought his own too.

In the absence of accounts of Cavendish at
Cambridge, we have to fall back on the usual life of
a Peterhouse undergraduate at the time to give
some idea of his. An undergraduate dined off
pewter and ate mutton five times a week and at all
meals drank ale and beer, which was brewed at a
profit by the college butler. Service was spare but
again hierarchical: for the relatively few fellows and
fellow-commoners, the butler kept four tablecloths,
whereas he kept only two for all the rest, pen-
sioners and sizars combined. 32 It was cold indoors;
in the year Cavendish came up, 1749, it was ruled
that a fire was to be made in the combination room
from noon to two o'clock. Prayers were given at six
in the morning and again at six at night, supper was
at eight, and at ten the college closed. Heads were
barbered by a barber appointed by the college.
When students ventured outside the college gates,
they found themselves in a very small town,
Cambridge, with shops that made money off them,
selling them wine, candles, gentlemen's wear,
books on law and medicine, and pens, pencils, and
paper. Cambridge could be dark, chilly, and dreary.
Fellow-commoners had extra money, which helped
or hindered them depending on how they used it,
in study or in idleness."

The fellow-commoner was privileged in
some ways but not in all ways. He was not excused
from the acts, opponencies, Senate House Exami-

nation, and religious tests at the end of his studies, if
he wanted a degree, but since a degree was unlikely
to make any difference in his life, he usually left
without taking one. That is what Henry Cavendish
did, in February 1753. It has been suggested that he-
objected to the religious tests, 34 which were stringent,
but if so there is no proof. A likely reason why he
left without a degree was the exercises in Latin and
the examination, which would have required him to
sit in the Senate House for three days at the mercy
of any M.A. who wanted to ask him questions, an
unimaginable horror for the shy Cavendish. 35 An
even more likely reason was that he did not even
consider a degree but simply followed tradition. Of
the thirteen fellow-commoners at Peterhouse
during Cavendish's stay, only four took degrees, and
three of these were pro forma Masters of Arts only. 3 ''
The examination that Cavendish did not
take was on its way to becoming the famous
Cambridge mathematical tripos. In fact, beginning
in the year Cavendish would have taken it, 1753,
the list of examinees was divided into wranglers
and senior and junior optimes, and there was lively
competition for a high position on it. Mathematics
had become the main discipline and almost the
sole subject of the examination, having taken the
place in the curriculum once held by logic.
Bolingbroke wrote to his son (who happened to be
at Oxford, not Cambridge) in 1748: "I am glad to
hear that you are at present applied to pure
mathematics; they give a proper exercise to the
mind, fix the attention of it, and create the habit of
pursuing long trains of ideas, the benefit of which
you will reap on subjects much more to your
purpose." 37 Mathematics toughened the mind for
entering the world of men, but it also illuminated
the system of the physical world and with it the
divine order. 38 This system was first and foremost

"'Winstanlcy, / 'unformed ' C.iimbridgf. 269-70.
"Walker, Admissions. 269-72.
'-Walker. Peterhouse, 79-80.
"Ibid. 79-85.

^Wilson, Cavendish, 17. 181.

"Winstanley, I'nrefortned Cambridge, 43—49. 199.

"Walker, Admissions, passim.

"Viscount Bolingbroke to his son, Frances, 10th earl of
Huntington, 24 Oct. 1748. Great Britain. Historical Manuscripts
Commission, Report on the Manuscripts of the l.nle Reginald Raaden
Hastings, Esq., of the Manor House. Ashby de la /.ourhe, 4 vols. (London:
His Majesty's Stationary Office, 1927-48) 3:65-66.

,M \Vinstanley, U unformed Cambridge, 48-51, 132. John Gascoigne,
"Mathematics and Meritoc racy : The Kmcrgcncc of the Cambridge Mathe-
matical Tripos," Social Studies of Science 14 (1984): 547-84. on 568-72.

//J

Cavendish

Newtonian. John Green, bishop of Lincoln, writing
in 1750 while Cavendish was a student, observed
th at at Cambridge, "Mathematics and natural
philosophy are so generally and exactly understood,
that more than twenty in every year of the
Candidates for a Batchelor of Arts Degree, are able
to demonstrate the principal Propositions in
/Newton's/ Principia; and most other Books of the
first Character on those subjects." '''

Given the mathematical emphasis at
Cambridge, there were naturally some very able
mathematical teachers there, such as John Lawson
of Sidney Sussex College, who was mathematical
lecturer and then tutor when Cavendish was a
student. 4 " Also given the very general purposes of
mathematical education, students who distin-
guished themselv es in mathematics would as a rule
go on to careers that required no mathematics. If
Cavendish had taken a degree, his competition in
the examinations of 1753 would have included
William Disney, Thomas Postlethwaite, and John
Hadley. The first two became writers on religion
and made their careers in Cambridge; the third
became a physician and professor of chemistry at
Cambridge. Disney, first wrangler, later regius
professor of Hebrew, published against Gibbon's
history of the Roman Empire and for the superiority
of religious duties over worldly considerations. 41
Postlethwaite, third wrangler, later master of Trinity
College, published only one work, a discourse on
Isaiah, while retaining his reputation as one of the
best mathematicians in the university. 4 - Hadley,
fifth wrangler, a good friend of Henry Cavendish,
comes up later.

Whereas Lord Charles Cavendish learned
mathematics by private lessons from mathematicians
who were Newton's associates, Henry Cavendish
learned mathematics at Cambridge, if not elsewhere
too. Whether or not he had a mathematically adept
tutor or attended lectures on mathematics, for over
three years he was exposed to the mathematical
tradition of Cambridge and to the books listed
in the various editions of the student guide at
Cambridge 45

Cavendish was the only major English ex-
perimentalist of the second half of the eighteenth
century with a Cambridge mathematical educa-
tion, and to that degree his work was markedly
different than his contemporaries'. From his ear-
liest researches, he demonstrated his mastery of

mathematics, revealing a strong imprint of his
Cambridge years.

The one record we have of Cavendish's
thinking while he was at the university brings
together education, politics, and science. Frederick,
prince of Wales, after holding court in opposition to
his father, George II, for nearly fifteen years, died
while still waiting his chance. The royal misfortune
was an excuse for academic exercises at Cambridge
and with them Henrv Cavendish's first publication.
His "Lament on the Death of Most Fminent
Frederick, Prince of Wales" was written in Latin, and
as a poem it met the standard of the day, which was
not high. Horace Walpole made a play on words:
"We have been overwhelmed with lamentable
Cambridge and Oxford dirges on the Prince's

death ' <44 The premature death of a prince was

an appropriate occasion to reflect on the fragility
and vanity of life. 45 Tears are fruitless, Cavendish
wrote; the thistle and the lily alike flourish, death
plays no favorites. The middle stanza, however, is
not conventional. Here we hear the scientist speak,
the "intimate" of nature: while nature may mock
us. Cavendish wrote, it "does lay bare hidden
causes, and the wandering paths of the stars." 4 ''

Learning Science

Very few eminent British scientists were
like Cavendish upper class. 47 Philip Stanhope —

"John (irccn. Academic, 1750. p. 25; quoted in Christopher
Wordsworth, Scholae Academicae. Some Annum of the Studies tit the
English Universities in the Eighteenth Century (London: Frank Cass
reprint. 1968), 75.

4 "La\\son published a number of books on mathematics in the
1760s and 1770s. "Lawson, John," DSB 11:736-37.

■"Nichols. Literary Illustrations 6:737.

■•-"Postlethwaite, Thomas." DNB 42:204-5.

•"Daniel VVaterland, Advice to n Young. Student. With n Method of
Study for the Four hirst Years, 1706-40; reported in Wordsworth,
Scholae Academicae, 78-81, 248-49, 330-37.

■"Horace Walpole to Horace Mann, IN June 17.51. Horner
Walpole's Correspondence, vol. 20. parr 4, pp. 260-61.

45 As did the future life scientist Erasmus Darwin, who was at
Cambridge at this time: in Darwin's lament, Neptune tells people to
stop mourning since the prince might be in Jove's court and wearing
a smile. Darwin was admired for this writing. Desmond King-Hele,
Doctor of Revolution. The Life and Genius of Erasmus Darwin (London:
Faberand Faber, 1977), 27.

^Cavendish's verse appears in the collection: Cambridge
I Iniversity, Academiae Cantabrigiensis Lucius in Obitum Frederici
celsissimi Walliae Principis (( Cambridge, 1 751 ).

■"Hans, New Trends. 54. groups Del-aval with Cavendish and
Boyle as the three eminent scientists out of 680 British scientists,
most chosen from the Dictionary of National Hiography. who were
"sons of peers." Cav endish was not. of course, the son of a peer, but
the point is made of the rarity of aristoc rats in this company,

Copyrighted material

Education of Henry Cavendish

113

not the mathematician Stanhope who was Charles
Cavendish's friend, but the famous essayist, the
earl of Chesterfield — advised his son on what to
know and what not to waste his time knowing, in a
letter written in 1751, when Henry Cavendish was
at Cambridge. Stanhope had just brought the bill
in the House of Lords to change the calendar from
the Julian to the Gregorian. He knew nothing
about astronomy but he gave a good speech
anyway, one which was considered more effective
than the accompanying speech by Macclesfield,
who did know what he was talking about. The
reason for his success, Stanhope told his son, was
his words and periods, his eloquence. Reason and
good sense made no impression in politics, he had
observed. It was all right if his son learned a little"
astronomy and geometry so that he would not
appear ignorant in conversation, but six months
were all he needed for that. Stanhope said he
would rather talk with captains in the military than
with Newton or Descartes. Since manner was
everything, Stanhope advised his son to read
Bolingbroke on style. 48

Henry Cavendish was set apart from most
of his scientific colleagues by education as well as
by class. The fraction of eminent British scientists
in his time who had a Cambridge or Oxford
education was small and steadily falling. 49 Still
there were a few young men of future scientific-
achievement at Cambridge when he was there.
One of them was Edward Delaval, younger brother
of a peer from an ancient Northumberland family,
who would become a chemist, a recipient of the
Royal Society's Copley Medal and another gold
medal from the Manchester Literary and Philo-
sophical Society. Because of Delaval's scientific-
interest, his station, his residence (his college,
Pembroke, was across the street from Peter-
house), and his voice (which was resounding, a
family trait, earning him the local name of
"Delaval the loud"), Cavendish could not have
failed to know him or about him; he was to
receive the Copley Medal of the Royal Society
with Cavendish.™ One year younger than Caven-
dish, Nevil Maskelyne, a student at Trinity
College, would go on to a distinguished career in
astronomy, first as assistant to James Bradley and
then in Bradley's post of astronomer royal; he was
also to become one of Cavendish's most valued
colleagues. At Cambridge and also of about the

same age as Cavendish were the promising but
short-lived chemist John Hadley, the capable prac-
tical astronomer Francis Wollaston, who graduated
second wrangler, and the eccentric mathematician
Francis Maseres, who graduated first wrangler and
coveted the Lucasian chair that went instead to
Edward Waring. Hadley was a guest in the Caven-
dish home, and Cavendish recommended both
Wollaston and Maseres — and in both cases he was
first to sign the certificate — for membership in the
Royal Society. 51

Of eventual importance to Cavendish as a
friend and colleague was another young man at
Cambridge, John Michell. Having graduated the
year before Cavendish entered Cambridge, Michell
was a fellow of Queen's College, where he gave
lectures. Unprepossessing in appearance ("a little
short man of a black Complexion, and fat"),
Michell was described by a contemporary diarist as
a "very ingenious Man and an excellent Philosopher,"
which he was. 52 While Cavendish was at Cambridge,
Michell was doing research in natural philosophy
and keeping in touch with the wider world. Having
made a thorough investigation of the properties of
the magnetic force and having published a method
for making strong magnets artificially in 1750, that
year he invited scientific men to Cambridge to
observe his experiments."

w F-arl of Chesterfield to his son Philip, IK Mar. and 7 Apr. 1751,
and 19 Sep. 1752, in Letters Written by the Late Right Honourable Philip
Dormer Stanhope, Earl of Chesterfield, to His Son, Philip Stanhope, Esq;
Uite Envoy Extraordinary at the Court of Dresden: Together with Several
Other Pieces on Various Subjects, ed. K. Stanhope, vol. 2 (Dublin, 1774),
118-22, 127-30, 285-88.

49 Hans, New Trends, 34. estimates that the proportion of scientific
Oxford and Cambridge graduates dropped from 67 percent in the
seventeenth century to 20 percent at the end of the eighteenth cen-
tury. I Ians's figures do not have much significance, since they arc-
based on rather arbitrary definitions, but the large fraction of
scientific practitioners in Henry Cavendish's time who were not
Oxford or Cambridge graduates is significant.

5°The name was given to Delaval by his friend Thomas Gray.
Cremer, Cray, 142^43. Two years older than Cavendish, Delaval took
his M.A. and became a fellow of Pembroke. "Delaval, Edward
Hussey," DNB 5:766-67.

51 Royal Society, Certificates 3:65 ( Francis Wollaston 's
announced candidacy, 3 Jan. 1769) and 3:104 (Francis Maseres 's
announced candidacy, 31 Jan. 1771).

"The diarist William Cole is quoted in Archibald Geikie,
Memoir of John Michell (Cambridge: Cambridge University Press,
1918), 8.

"Michell recalled this visit to Cambridge in 1750 by John
Canton, John FJlicott, and another person in connection with a
priority dispute: letter of 17 May 1785 to the editor of the Monthly
Rninc: pp. 478-80. on p. 47'<

114

Cavendish

In the introduction, wc discussed Lord Charles and
Henry Cavendish in relation to two revolutions,
one political and one scientific. The education that
Henry received at Cambridge can be related to
those revolutions, too. By that time Newton's
natural philosophy, as presented in the Principia,
had come to be taught as an integral part of the
curriculum at Cambridge, and it has been argued
that one of the reasons for this curriculum is a
change brought about in the university by the
Glorious Revolution. After the Revolution,
Cambridge became a stronghold of low-church
latitudinarians and whigs, to whom Newtonianism
had a particular appeal (for the support it gave to
the argument from design). 54 It is certainly the case
that Cavendish was indoctrinated in a scientific
orthodoxy originating in the scientific revolution in
an institution sympathetic to the Revolutionary
Settlement. For some three odd years, Cavendish
lived and breathed Newtonianism.

Just as the university was dominated by its
colleges, its teaching was dominated by tutors in
their colleges and not by the small number of
professors of the university. In critical and historical
accounts of the university in the eighteenth
century, the professors have generally fared poorly,
judged even less important than their numbers
would suggest, and derogated if not treated as
figures of fun. Professors sometimes deserved this
treatment, but it can be said on their behalf that
their teaching was becoming increasingly marginal
as their subjects were being taken over by the
tutors. They were deprived of the usual incentive
to lecture, though some of them took this form of
teaching seriously all the same, and almost all of
them brought out textbooks. Of interest to us are
certain professors whose subjects would have been
of interest to Cavendish.

Whether or not Cavendish heard Cambridge
professors lecture, he most certainly knew their
textbooks and their common desire to build
science on Newton's example. Just what a
scientifically minded student like Cavendish made
of it was, ultimately, up to him. Just as Cavendish
had to start somewhere, so must we: in this chapter
we examine some textbooks by professors used at
Cambridge and in this way learn, as students in
Cavendish's day learned, the approved way of
studying nature.

The great influence of Newton on Cambridge

was through his physical theories, the mathematical
theorems of which were the main study when
Cavendish was there. 55 The philosophical power of
the mathematical description of nature was
demonstrated — once and for all time, his followers
believed — by Newton in his treatise Mathematical
Principles of Natural Philosophy, which appeared in
three editions in Newton's lifetime, with changes
in technical and philosophical content, between
1687 and 1 726. v> The complementary power of the
experimental enquiry into nature was as persuasively
demonstrated in Newton's optical researches, col-
lected in his treatise Optich, which also appeared in
three editions, between 1704 and 1717/18. This
latter book had a speculative part, "queries," which
was enlarged in each edition. Its purpose being to
stimulate others to carry forward the investigation of
nature in Newton's mathematical and experimental
way, it was regarded as the most important part of
the book by Newton's followers in the eighteenth
century. 57

By contrast with his principal physical
writings, Newton's published mathematical writings
at the time of his death amounted to a few
scattered tracts, which by no means revealed the
extent of his researches. In the beginning of the
Principia. he introduced the mathematical ideas
needed for understanding what followed, and to
the first edition of the Optich he appended two
Latin treatises on curves and their quadrature,
which a few years later reappeared in English
translation. It was left to others to bring out certain
other of Newton's mathematical writings, the
existence of which was known, since Newton lent

SJ John Gascoigne, Cambridge in the Age of the Enlightenment:
Seienee, Religion and Polities from the Restoration to the Frenrh Revolution
(Cambridge: Cambridge University Press, 1989), 145.

SS W. W. Rouse Ball. A History of the Study of Mathematics at
Cambridge (Cambridge, 1889), 74-76.

% 'l he editors of the three editions of New ton's treatise
(generally referred to by the short Latin title Principia) were early
disciples of Newton: Halley in 1687, Roger Cotes in 1713, and Henry
Pembercon in 1726. In 1729 an English translation was brought out
by Andrew Motte: Sir Isaac Newton's Mathematical Principles of Natural
Philosophy and His System of the World, rev. F. Cajori, 2 vols. (1934;
Berkeley and Los Angeles: University of California Press, 1962). I. B.
Cohen, Introduction to Newton's Principia (Cambridge: Cambridge
University Press, 1971), vii, 7.

"The editions were the first, in 1704, in English; the seeond, in
1706, in Latin; and the third, in 1717/18, in English again. Isaac
Newton. Opticks; or a Treatise of the Reflections, Refractions, Inflections &
Colours of Light, based on the 4th ed. of 1730 (New York: Dover
Publications, 19.S2). I. B. Cohen, "Newton, Isaac," DSB 10:42-101
on 59.

Copyrighted m aerial

Education o f Henry Cavendish

out his mathematical manuscripts. William Whiston,
Newton's successor at Cambridge, published
Newton's Arithme/ica Universalis in 1707, and in
1711 he published short works by Newton on
fluxions and infinite series, under the title Analysis
per Quantitatum Series, Fluxiones ac Differentias. . .
William Jones's copy of Newton's systematic-
account of the method of fluxions was published in
English translation by John Colson, holder of
Newton's Lucasian chair in Henry Cavendish's
time. Roger Smith, the Plumian professor of
astronomy and experimental philosophy then,
discovered more mathematical manuscripts by
Newton, though he did nothing with them. 5 *
Newton was gone but his works appeared as if he
were still among the living. Other than in stature,
Newton did not seem distant to people at
Cambridge when Cavendish was there.

The Principia lays down the laws of matter
in motion and the law of universal gravitation, with
which Newton deduced the motions of the planets,
comets, moon, and tides. 59 Its sweeping deductive
power was the basis of its appeal. 60 The laws of motion
were presumed to contain all relations between
matter, motion, and force in the sense that all
theorems of geometry are contained in the axioms
of that subject. In addition to gravitation, other forces
were known to exist, which had yet to be described,
which defined for Newton the "whole burden of
philosophy": it was to observe the motions of
bodies and from them to deduce the forces acting
and then to deduce from these forces the other
phenomena of nature/' 1

For the phenomena, Newton drew mainly
on known empirical laws and on available
astronomical observations. He kept his discussion
of experiments separate from the mathematical
development, consigning them to "scholiums," the
purpose of which was to make clear that the
mathematical propositions were not "dry and
barren." 62 Newton reported exacting experiments
of his own on pendulums, but he revealed himself
as the proven master of experimental enquiry as
the anchor of the Opticks.

Like the Principia, the Opticks begins with
definitions and axioms. However, a glance at its
pages reveals that it contains an orderly progression
of experiments and that it ends with a series of
questions. It argues experimentally for a new
understanding in optics, which Newton had earlier

115

announced in the Philosophical Transactions: the
white light of the sun is compounded of
heterogeneous colored rays, and these colors arc
original and immutable qualities of light, and they
are quantitatively distinguishable by their different
degrees of refrangibility upon passing through
bodies. For the explanation of the bending and
reflecting of light by bodies, Newton looked to the
subject of his earlier treatise, forces and motions.
Between the rays of light and bodies, a force acts;
the only uncertainty was "what kind of Force," 6 '
and for that to be known, "both /light and bodies/
must be understood." Newton did a variety of
experiments on the interaction of light and bodies:
on the colors of thin, transparent bodies, and on the
inflexion of light by a knife edge. The book ends
inconclusively. Newton did not have a complete
"Theory of Light," only the beginning of one. The
sixteen queries of the first edition complete
Newton's design insofar as they suggest how the
science might look when completed, after the
optical forces had been subsumed under
mathematical law as had the force of gravitation.
The Opticks returns to the Principia, to the ideal of
the derivation of all motion from force, but the
problem optics posed was obviously more difficult
than the one astronomy had. The bodies of the solar
system moved in regular ellipses and parabolas; in
the queries, Newton spoke of light passing near
bodies as having a "motion like that of an Eel." 64

Heat, one of the consequences of the action
of light on bodies, is the subject of nearly half of
the first set of queries in Newton's Opticks. By the
law of action and reaction, the third of Newton's
laws of motion, the reflection, refraction, inflection,
and emission of light by bodies induce an agitation
of the small parts of the bodies. Heat, for Newton,
is that agitation, an internal vibration. 63 The rest of

5S D. T. Whiteside, in his edition of Isaac Newton, Mathematical
Papers of Isaac Stwton, vol. 1 (Cambridge: Cambridge University
Press, 1%7), xv-xvi, xxv, 33.

v ' The discussion that follows of Newton's Principia and Opticks
is taken largely from the section "Newton's Science," in Russell
McCormmach, " The Electrical Researches of Henry Cavendish,"
Chi), diss.. Case Institute of Technology, 1967, on 5-29.

M C. Truesdell, "A Program Toward Rediscovering the Rational
Mechanics of the Age of Reason," Archive for History of Exact Sciences
1 (1960): 1-36, on 6.

M Newton, Mathematical Principles, 1 :xvii— xviii.

"Ibid, 2:397.

"'Newton, Opticks, 82, 276.
«lbid, 339.
"Ibid, 339.

116

Cavendish

the queries have to do with the action of bodies on
light and on the optic nerve and the physiology of
color vision.

In the second edition, Newton added seven
more queries, which constitute the fullest statement
of his expectations for the mechanics of the forces
between particles of bodies and of light. A final set
of eight queries on the ether w as added to the third
edition. Backed by Newton's authority, the queries
of the Opticks proved to be a source of new science
(and of dead ends) for readers throughout the
eighteenth century.

Newton's Principia became a canonical text
at Cambridge. Even if only the early propositions
had to be mastered, students found it hard going,
which gave their teachers something to do. They
lectured, tutored, and wrote texts on Newton's
work for the learners.

One of the first to lecture on it at
Cambridge was William Whiston, who wrote
several books still in use at Cambridge when
Cavendish was there. An ambitious man of wide
interests and fervid commitments, Whiston's
discovery of Newton carried the force of a
conversion. After he had studied mathematics at
Cambridge and had taken holy orders, he returned
to Cambridge, there to join the "poor wretches," as
he recalled in his Memoirs, who were still studying
Descartes's fictions. He had actually heard Newton
lecture a time or two without understanding a
word. It was upon reading a paper by the
astronomer David Gregory that Whiston became
aware that Newton's Principia was the work of a
"Divine Genius." With "immense pains" and
"utmost zeal," Whiston tackled the Principia on his
own. Wl An early result of his discovery of Newton
was his book A New Theory of the Earth, which he
submitted and dedicated to Newton, "on whose
principles it depended, and who well approved of
it." Drawing upon Newton's triumphant reduction
of comets to mathematical law and otder in the
Principia, Whiston demonstrated the book of
Genesis. The earth, originally a sun-bound comet,
was struck by another comet, which caused the
Deluge and at the same time its present elliptical
path and diurnal rotation. These cosmic events
were the expression of God's will, but the physical
agency was New ton's universal gravitation.'' 7 When
Newton left Cambridge for his post at the mint in
London, in 1701 he arranged for Whiston to

succeed him as Lucasian professor of mathematics.
Whiston published his lectures at Cambridge on
astronomy and on natutal philosophy, the latter the
first extensive commentary on Newton's Principia.
And, as we said, with Newton's approval, he
published Newton's lectures on universal arithmetic,
or algebra, which presented the subject with
intellectual grandeur and pedagogic practicality.
Newton asserted that arithmetic and algebra make
"one perfect science," with algebra distinguished by
its "universal" character, allowing general theorems
and giving it power over particular arithmetic for
solving "the most difficult problems." The material
is presented according to Newton's method in
teaching: "in learning the sciences, examples are of
more use than precepts."'* Whiston eventually fell
out of favor with Newton (and Cambridge), but
Newton had done much for him, placing him at
Cambridge as his successor and showing him his
favor for many years, which Whiston reciprocated
by implementing Newtonian studies at Cambridge.'' 1 '
While he was Lucasian professor, Whiston
let the young scholar Nicholas Saundcrson lecture
on the same material, Newton's Universal Arithmetic,
Principia, and Opticks. Blind virtually from birth,
Saundcrson demonstrated, his publisher said, how
far the faculties of the imagination and memory
could compensate for the want of a sense. He was a
kind of prodigy and living experiment of the

"'William Whiston. Memoirs (London, 1749), 57.

'"William Whiston. .1 New Theory of the Earth . . ., 5th ed.
(London. 1 7.57): Memoirs of the Life mitt Writings of Mr. William Winston
(London. 1749). 4.V Jacques Roger, "Whiston. William." DSB
14:295-96.

"Whiston's edition of" Newton's lectures appeared in Latin in
1707 and was translated by the mathematician Joseph Ralphson,
Universal Arithmetici; or, A Treatise of Arithmetical Composition and
Resolution . . . (London. 172(11. Most of the problems Newton
discusses are geometrical, but some are mechanical; e.g.. problems
12 and 16, on elastic collisions and the position of a comet.
References to the Knglish edition, pp. 1-2. HO, 1 17. 191.

'''Whiston was banished from Cambridge in 1 710 for unorthodox
religious beliefs, which he made public; this time he did not receive
help from Newton, who held similar beliefs but kept them private.
Whiston published his astronomical lectures in 1707: Praelectiones.
Astronomicae, translated in 1715 as Astronomical Lectures, Rend in the
Publick Sehools of Cambridge . . .: these lectures speak of "attraction"
and Newton's theory of the moon, but they are not so much a
Newtonian text as the astronomical preparation for Newton's
philosophy, which Whiston promised to give next term, lie
published his lectures on natural philosophy in 1710. Praelectiones
Physico-Mathematicae, translated in 171b as Sir Isaae Newton's
Mathentatic Philosophy More Easily Demonstrated. Maureen Farrell,
William Whiston (New York: Arno. 1981), 200. Rouse Ball, History,
85-X5. 94-9.5. "Whiston. William," DXH 21:10-14. Whiteside,
Newton's Mathematical Papers l:xvi.

Education of Henry Cavendish

Enlightenment. He definitely was a source of local
wonder, able to distinguish a fifth part of a musical
note, estimate the size of a room from the sounds
in it, tell the difference between genuine and false
medals by touch, and, most important, gain great
proficiency in higher mathematics. Elected
Whiston's successor in the Lucasian chair,
Saunderson had good relations with the scientific
circle associated with Newton: Cotes, Jones, De
Moivre, Machin, John Keill, and others. Like
Whiston, Saunderson 's importance was not as an
original mathematician but as an industrious teacher
of the new mathematics and natural philosophy at
Cambridge. Saunderson did not publish any books
himself, but soon after his death, his lectures on
fluxions and algebra were published. When Caven-
dish entered Cambridge, various of Saunderson's
lectures in manuscript were still in circulation, parts
of which had been published under others' names.
Even several years after Cavendish had left
Cambridge, Saunderson's lectures could still be
promoted as the best presentation for university
students. 70

Saunderson was known to have revered
Newton, whose work he made the basis of his
teaching. Saunderson's Method of Fluxions begins
abruptly with a proposition about triangles, the
sides of which are identified with Newtonian
forces. His subject, fluxions, was the new, powerful
mathematics of the natural world. Like their in-
ventor, Saunderson defined fluxions with reference
to motion: fluxion x is the velocity of a flowing quantity
x, the familiar wording and image. Saunderson
referred to some experiments on air, but for the
most part he treated only the mathematical part of
natural philosophy, weaving together fluxions,
algebra, geometry, and mechanics as one in-
separable subject. Saunderson's way of teaching
mathematics entailed a way of thinking about nature,
the lesson a Cambridge student in the middle
of the eighteenth century would have drawn from
his lectures. 71

Upon Saunderson's death in 1739, the aging
De Moivre (who looked to one observer as if he
were "fit for his coffin ... a mere skeleton") and
Whiston (who wanted to return but was not taken
seriously) were passed over for the mathematical
schoolmaster John Colson as the new Lucasian
professor. 72 Besides teaching, Colson had taken a
modestly active part in the science of his day; his

principal claim to the Lucasian chair was his
publication three years before of the tract Newton
had wanted to publish but for which there was no
market, The Method of Fluxions and Infinite Series.
Long circulated in Cambridge, Newton's manu-
script was translated from Latin into English by
Colson, and as we said, for this purpose Colson
used a copy owned by William Jones, to whom he
warmly dedicated the publication. 73 The Cambridge
diarist and antiquarian William Cole got it right
when he described Colson as a "plain honest man
of great industry and assiduity." 74 If he disappointed
people at Cambridge, as Cole said he did, it was
not by his lack of original mathematics but "by his
lectures." In Colson, Cambridge had acquired a
known quantity: he remained what he had always
been, essentially a teacher.

Whatever might be said of Colson's
accomplishments, his enthusiasm for his subject and
its inventor cannot be faulted. His words in the
annotated edition of Newton's Method of Fluxions
stand out even among the most excessive
Newtonian panegyrics. Mathematics was the greatest
of all intellectual attainments, Colson said, and

7 "Rousc Ball. History, 86. "Saunderson or Sanderson, Nicholas,"
/XV/? 17:821-22. Roger Cotes to William Jones, 25 Nov. 1711, and
Nicholas .Saunderson to William Jones, 4 Feb. ] 713/14, in Stephen
Jordan Rigatid. ed.. Correspondence of Scientific Men of the Seventeenth
Century, vol. 1 (Hildesheim: Ceorg Olms reprint, 1965), 261-62. on
261, 264-65, on 265.

71 Nicholas Saunderson, The Method of Fluxions Applied to a Select
A umber of Vseful Problems; . . . and an Explanation of the Principal
Propositions of Sir Isaae Sewtons Philosophy (London. 1756), ix-x, 79,
81, and Advertisement. "Saunderson," DNB 17: 821. Like Newton's
lectures, Saunderson's were a set of examples; that was how they
were described by the Cambridge astronomer William Ludlam, who
knew them firsthand, having been one of Saunderson's pupils
engaged in reading sections of New ton's Principia. William Ludlam,
The Rudiments of Mathematics; Designed for the Use of Students at the
Universities (Cambridge, 1785), 6.

'-Quotation about De Moivre 's age and infirmity from William
Cole's diary, quoted in "Colson, John." t).\'H 4:801-2, on 801. From
1709 until he was named Lucasian professor, John Colson taught at
Sir Joseph Williamson's Mathematical School, in Rochester. He has
been confused with a relative of the same name who headed a
mathematical school in London from 1692; early on. the younger
John Colson may have taught at that school too. R. V. and I'. J. Wallis,
Biobibliognphy of British Mathematics and lis Applications. Part 2:
1701-1 760 (New castle upon Tync: Kpsilon I'ress. 1986), 35.

"In 1758 Colson translated from the French a theoretical paper
by Alexis Clairaut on the figure of the planets for the Philosophical
Transactions. Before that, he had published two mathematical papers
of his own on algebra and another on spherical maps in the same
journal, and one of the algebra papers had been translated into Latin
and appended to the 1752 Leydcn edition of Newton's Arithmetic!!
Universalis. "Colson," DNB 4:801-2. Rouse Ball, History, 100-1.
Whiteside, Newton's Mathematical Papers l:xv, 8:xxiii.

"Quoted in "Colson." DNB 4:801.

Cavendish

one obvious Cavendish who was not in Henry
Cavendish's will was, formally speaking, the first
and most expectant Cavendish of them all, the
tenant for life of the vast family estate, the fifth
duke of Devonshire. Lady Sarah Spencer,
Ceorgiana's niece, speculated on why Henry
Cavendish forgot the duke's existence in his will:
perhaps Cavendish "thought that said existence
was something of a disgrace to the noble name of
Cavendish," 138 as well he might have. The
Cavendishes, including Henry, were a family of
achievement, with the notable exception of the
fifth duke. The last two male Cavendishes of the
next generation were 1 loratio Walpole, second earl
of Orford, and Ceorgc Walpole, sons of Rachel
Cavendish. For the name Walpole to appear with
the name of Cav endish might be regarded as the
final legacy of the second duke of Devonshire to
his family. His career had been inseparable from
that of Robert Walpole, and the Cavendish in-law
Walpoles were relativ es of the prime minister. But
we have no idea if Henry Cavendish associated
with them in any way. From the Crey side of his
family, there were three living members of
Cavendish's generation, John William and Francis
I lenry Fgerton, the seventh and eighth earls of
Bridgewater, and John, second earl of Ashburnham,
and in the next generation there was Ceorge, the
future third earl of Ashburnham. The two earls of
Bridgewater were Fellows of the Royal Society,
and Francis Henry, the eighth earl, is well known
to historians of science as the founder of the
Bridgewater Treatises, the authors of which were
selected by the president of the Royal Society and
the Bishop of London to demonstrate the "Power,
Wisdom, and Coodness of Cod, as manifested in
the Creation." 139 This clergyman was strongly
interested in science but not in a way that would
have brought him and Henry Cavendish together.
Lord Charles Cavendish kept a correspondence
with his sister-in-law Lady Ashburnham, Jemima
de Crey, 14,1 but we have come upon no record of
contact between Henry Cavendish and the
Ashburnham or Bridgewater families. The second
and third earls of Ashburnham w ere tories, but that
would not have been a main consideration. Henry
Cavendish saw to it that his wealth remained
within the Cavendish family; his will made perfect
sense, its surprises merely minor variations on the
standard theme.

Lady Sarah Spencer did not regret that the
duke of Devonshire gained nothing from Cavendish's
death, since he and his heir, Harrington, were
"pretty veil off." 141 The duke's complaint about
Cavendish's will had to do with ritual. The
scientists, however, believed that they had a
substantial complaint. Cavendish received more
criticism in death than he had in life, in particular
for not leaving money to Davy. 14 - Davy himself had
expected it, Blagden thought:.

Davy said, Mr. C. has at least remembered one
man of science /i.e., Blagden/, in a tone of voice
which expressed much: & added that at the time
when Mr. C. made Hatchett much distressed &
much with him, so wondered he had not then
remembered him, to this I answered, it was not
likely that he slid leave to a man of" Hatchett's
expectations /Hatchett would become rich/.
Wollaston's countenance was unchanged. 145

There were rumors that even Blagden was
disappointed, that he had higher expectations, 144
but there is no evidence of this in anything he
wrote including his diary. Amidst the dis-
appointments in the days following Cavendish's
death, Blagden staunchly defended his old friend.

The funeral procession that Blagden
watched from his window set out with the body
from Clapham Common at seven in the morning
on March 8th. The train of carriages carrying
members of the family proceeded northward
through London on their way to Derby, 145 where
Cavendish was to be buried in the family vault
under the Church of All Saints. Before that the
procession would be met at the gates of the city by
twenty-four burghers and twenty-four constables
and a retinue of city officials (all of whom were
paid to do this) dressed in black. The pomp and
ceremony were invariable for the Cavendish dead,

IM Lady Sarah Spencer quoted in Hugh Stokes. The Devonshire
House Cirri,' (London: I lerbcrt Jenkins, 1917), 315.

"''Charles C. Gillispie, Genesis and Geology: A Study in the
Relations oj Scientific Thought, Natural Theology, and Social Opinion in
Great /In/am. 1790-1850 (New York: I larper & Row, 1959), 209.

I4 "llenry Cavendish. "Papers in Walnut Cabinet," Cavendish
Mss, Misc.

141 Stokes, Devonshire House Circle, 315.

I4 '5 and 6 Mar. 1810, Blagden Diary, Royal Society, 5:back p.
430 and p. 431.

' J, 8 Mar. 1810, Blagden Diarv, Royal Society, 5:back p. 431 and
p. 432.

'■"Henry, Lord Brougham. Lives of Men of Letters and Science Who
nourished in the Time of George III (Philadelphia, 1845), 250-59. on 258.

'•"Lord Bessborough to Charles Blagden. 7 Mar. 1810. Blagden
Letters. Royal Society, B.149.

IIS

Cavendish

Newton was the "greatest master in mathematical
and philosophical knowledge, that ever appear'd in
the world." The subject at hand, fluxions, in
particular, was the "noblest effort that ever was
made by the human mind." Newton's Method,
unlike his other mathematical writings, "accidental
and occasional," was intended as a text for "novices
and learners," a goal which the teacher Colson could
become enthusiastic about. Colson could not have
made a clearer distinction between textbook and
original work nor between a teacher like himself
and the author of great works like Newton, yet he
implied that the humble beginner could compre-
hend the work of the greatest thinker of all time —
false encouragement perhaps for many of his auditors
and readers but not for someone like Cavendish.
Colson's edition of Newton was at once a textbook
and an indoctrination into mathematical Newtonian-
ism, and it was also a book of advocacy, as Colson
eagerly enlisted in the ranks of Newton's supporters,
defending Newton and attacking his critics. 75

For the learner of fluxions and infinite
series, there was Newton's own presentation, and
then there was Colson's. If Newton's was terse,
Colson's was prolix; Newton's treatment of infinite
series occupies twenty pages, Colson's "perpetual
comment" ninety-eight. 7 '' Colson assumed little of
his reader, expanded freely on the text, gave copious
examples, and wrote not as a mathematician but as
an eternally patient teacher who repeated the
obvious as well as the essential. 77 We cannot know if
Cavendish read Colson's commentary as well as
Newton's text; but if he did, he read two obser-
vations that might stimulate a beginning mathe-
matical student. One was that Newton had not said
the last work on the subject: improvements in the
method of fluxions had been made since Newton,
and the subject was capable of further perfection.
The other observation had to do with Newton's
general method, that of analysis. In his tract, Newton
noted that modern mathematicians favored the
"analytical" method over the "synthetical." Colson
elaborated: by the ancient synthetical method, the
mathematician proceeds from truths already known,
proving them from axioms, whereas by the modern
analytical method, he proceeds from the known to
the unknown. Analytics is the "art of invention," a
method of discovery. 78

We turn now from the professors of
mathematics to the professors of astronomy and

experimental philosophy. Their chair was the more
recent of the two, endowed in 1704 by the
archdeacon of Rochester, Thomas Plume. Its
appearance coincided with the beginning of the
Newtonian school at Cambridge.

The acceptance of Newtonian teaching at
Cambridge began in 1699, soon after Newton had
left Cambridge for London, but before he had
resigned his Lucasian professorship, when the
mastership of Trinity fell vacant. The man elected
to fill it in the following year was the king's
librarian Richard Bentley, a classical scholar greatly-
impressed by the new science. 7 '' Not himself a man
of science, Bentley was a good judge of men who
were and also of their needs. Wanting to make

"Colson thought that the beginner's greatest difficulty was in
understanding the notion of a vanishing quantity. His patient
elucidation was intended to make this notion "rational." Colson had
a second purpose beside instructing: it was to prove the superiority
of Newton's vanishing quantity over the foreign. Leibnizian notion
of indivisibles, and to answer Bishop Berkeley's criticisms of
Newton's notion of quantity. To Colson, the resolution of the
controversy over the nature of quantity had the utmost urgency,
since it fostered distrust of science itself. To this end, Colson
explained the two principles of quantity in Newton's mathematics:
the first, taken from rational mechanics, is that mathematical
quantity can be conceived of as generated by local motion; the
second is that quantity is infinitely divisible. Newton, Colson says, is
to be trusted over his foreign rivals, with their infinitesimal method,
because Newton had a "compleat knowledge of the philosophy of
quantity." Colson's comments in his edition of Method of Fluxions.
ix-xii. xx, 335-36.

7 ''Colson was a teacher of a familiar kind, one who once has hold
of a subject cannot let go. His contemporary John Stewart, professor
of mathematics at the University of Aberdeen, published a
translation of two mathematical tracts by Newton with commentary.
The two tracts occupy 54 pages of Stew art's hook, and the rest of the
497 pages plus introductory matter is Stewart's commentary. His
book, like Colson's, was intended for beginners. Sir Isaac Newton's
Two Treatises: Of /lie Quadrature of Curves, and Analysis by Equations of
an Infinite Number of Terms, Explained . . . (London, 1745).

7 'One of Colson's main points is that the idea of quantity as
something generated by motion in time is not essential to Newton's
Method of Fluxions. l ime itself is a quantity and can be represented
by symbols and lines, so that in the final analysis Newton's method
does not depend upon time at all, only on geometry. Time, however,
is heuristic, aiding the mind to grasp the idea of quantity, and it is
because of the uniform How of time that New ton called his method
the method of "fluxions." Fluxions are a mathematical method
conducive to discovery. A second main point is that fluxions are the
proper mathematics for treating a pair of inverse "problems" that lie
at the heart of the science of motion. These problems arise from the
fact that the velocity of a point and the distance described by the
point mutually determine one another. They are: given the distance
continously described by a point at any time, the problem is to
determine the velocity; and given its continuous velocity at any time,
the problem is to determine the distance described. Corresponding
to the two problems are, respectively, the direct method fluxions and
the inverse method of fluxions (or in later terminology, differentiation
and integration).

'"Colson's edition of Newton's Method of Fluxions, I. 144.

"Rouse Ball, History. 75.

Copyrighted material

Education of Henry Cavendish

119

Trinity a center of experimental and observational
science, Bentley had a laboratory built there for
Newton's friend John Francis Vigani, who had
lectured on chemistry at Queen's and had been
named the first professor of chemistry at Cambridge
in 1702. Bentley succeeded in securing the new
Plumian professorship for his colleague at Trinity,
the young mathematician Roger Cotes. Bentley
then raised a subscription for an observatory to be
built over Trinity's entrance gate and for neighboring
rooms to be assigned to Cotes and to his assistant,
his cousin Robert Smith. To further his scientific
ambitions for Trinity, Bentley arranged for Whiston,
of Clare College, also to have rooms in Trinity next
to the gate under Cotes's observatory. 81 ' Trinity set
a precedent for other colleges; Bentley, more than
any other person, was responsible for the eventual
dominance of the Newtonian school of science and
mathematics at Cambridge.

Bentley bore the expense of a new edition
of Newton's Principia in 1713 and was himself
going to edit it, but sensibly the task was
reassigned to a proper mathematician, Cotes, who
wrote a preface for it that became a cardinal
document in the dissemination of Newtonian
thought. Three years later, in 1716, Cotes died
suddenly, at age thirty-three. He had published
only two papers at the time of his death, one on
logarithms, which Robert Smith included along
with some theorems of his own in a posthumous
edition in 1722 of Cotes's mathematical manuscripts,
Harmonia Mensurttrum. This publication testifies to
Cotes's exceptional promise, for which we also have
Newton's often quoted observation, "Had Cotes
lived we might have known something." To be
sure, had he lived, he might have inspired an
enduring mathematical school at Cambridge, for he
was one of the few British mathematicians capable
of it and one of the last for a long time.* 1

Cotes left another record of his scientific-
activity in the form of lectures. With Whiston, in
the observatory at Trinity, he gave experimental
lectures in natural philosophy, among the first to be
given in England. After Whiston's expulsion from
Cambridge, Cotes continued to give the lectures
by himself, and after Cotes's death, Robert Smith
kept them going. In 1738 Smith published Cotes's
lectures. Unlike Cotes's Harmonia Mensurarum,
written tersely in Latin and intended for a select
audience of skilled mathematicians, his Hydrostatkal

and Pneumatical Lectures was written expansively
and popularly. Readers could take in the limited
mathematics, his editor Smith said, "with as much
ease and pleasure, as in reading piece of history."
(Smith could not leave it at that but added
mathematical notes of his own.) 82

Cotes's lectures were mostly concerned
with air but also with hydrostatics because the two
subjects were so close. Hydrostatics and pneumatics
were experimentally studied by that most precise of
instruments, the balance. Gravitation, the new
acquisition of science, the force to which the
balance responds, gave Cotes's lectures their unity.
Gravity, Cotes wrote, "is a property of so universal
an extent" that even "air, which as I shall after-
wards shew, may be weighed in the ballance." The
elasticity of air Cotes explained by referring to the
Principia, to the place where Newton derived
Boyle's law (the proportionality of the density of air
to the compressing force) by assuming that
particles of air mutually repel with a force inversely
proportional to their separation. To explain the
phenomena of sound, the minute rapid waves in
the air, Cotes again referred to the Principia, to
Newton's a priori calculation of the velocity of sound
from its causes, in agreement with measurements
of the velocity by Halley and others. Cotes's principal
inspiration came from Newton: the Principia for its
mathematical demonstration of the subtle properties
of air, and the Opticks for its rich insights into the
working of the smallest parts of creation. He wrote
of the fecundity of the final query of the Opticks:
"Whoever will read those few pages of that excel-
lent book, may find there in my opinion, more

"""Bentley. Richard," DNB 2:306-14. on 312. A. Rupert Hall,
"Vigani, John Francis." IIS/I 14:26-27. James Henry Monk, The Life
of Richard Rentier), 2d ed., 2 vols. (London, 1833) 1:202-4. Whiston,
Memoirs, 133.

»'J. M. Dubbey, "Cotes. Roger." DSB 3:430-33. Roger Cotes.
Harmonia Mensurarum, sive Analysis t£ Synthesis per Rati on urn c**
Angutorum Mensuras I'romo/ae: Arredunt alia Opusrula Mathemaliia , ed.
R. Smith (Cambridge, 1722). Rouse Ball. History. 90.

■"Coles's intention was to exemplify the experimental
philosophy, and his method was first to demonstrate by experiment
and then to draw general conclusions, which meant reading his
lectures. To convey his method. Smith added to the published
lectures descriptions of experiments and drawings of apparatus.
"The Editor's Preface," in Roger Cotes, Hydrostatiral and
Pneumatical Lectures, ed. Roger Smith (London, 173K). The second
edition was published in Cambridge in 1747. For his joint course of
experiments with Cotes, Whiston wrote half of the lectures, but he
did not publish his. With Francis I [auksbee, Whiston gave
experimental courses in London after leaving Cambridge. "Cotes,"
/JAW 4: 102°.

120

Cavendish

solid foundations for the advancement of natural
philosophy, than in all the volumes that have
hitherto been published upon that subject." Cotes
concluded the four-week course with a lecture on
Boyle's "factitious airs." These were airs, or gases,
contained in bodies that could be freed from them
artificially by tire, explosion, dissolution, putre-
faction, and fermentation. At the time of the
lectures — which was before Stephen Hales's
work — Boyle's were the "best and almost only
trials which have yet been made concerning
factitious airs." Cotes told of Boyle's extraction of
airs from a v ariety of substances, animal, vegetable,
and mineral, and by a variety of means; for exam-
ple, chemical, as in mixing iron w ith the acids aqua
fords and spirit of wine. Cotes presented factitious
airs not as a closed subject for a textbook but as a
new, hardly begun subject full of experimental
challenge. Drawing on Boyle, Cotes extended the
exact science of pneumatics beyond its origins to a
vast, largely unknow n field of gaseous phenomena
attending chemical actions. 83 We know that
Cavendish read Cotes's lectures, since he cited
them in his first publication, which was on, as it
happened, factitious air.

In 1716 Robert Smith was elected to
succeed Cotes. Smith was twenty-seven, and for
the next forty-four years he was the Plumian
professor at Cambridge. He also became master of
Trinity after Bcntley, and like his predecessor he
promoted science in Cambridge in every way he
could think of. Before becoming master, he had
lectured, and afterwards he took on able students,
lor example, to encourage Richard Watson, later
professor of chemistry at Cambridge, Smith ap-
pointed him to a scholarship, urged him to read
Saunderson's Fluxions and other mathematical
books, and gave him, Watson said, "a spur to my
industry, and wings to my ambition." Israel Lyons,
w ho liv ed in Cambridge, showed such mathematical
promise that Smith offered to put him through
school. s4 When Cavendish studied at Cambridge,
he would have been aware that the Plumian pro-
fessor was one of the founders of New ton's science-
through his teaching at Cambridge.

With the strong Newtonian direction at
Cambridge in the first half of the eighteenth
century, the holders of the Lucasian and Plumian
professorships might have been mathematical
astronomers and dev elopers of rational mechanics.

but this was not the case. The most important
scientific publication to come out of Cambridge-
was strongly Newtonian but the subject was optics,
Robert Smith's A Compleat System of Opticks,
published in 1738. We know that this book was in
the Cavendish library at Great Marlborough Street,
since Lord Charles Cavendish was one of the men
of science who subscribed to it. 85 The confidence-
implied by the subscription proved fully justified,
for this book was probably the most influential
optical textbook of the eighteenth century. 86

When Smith published his System of Optirh,
Newton's Optirh was nearly thirty-five years old.
Newton's treatise was meant as a scientific work,
and though the early experiments on the analysis
of white light into colored rays were accessible to
learners, the rest of the book addressed the most
difficult problems of the interaction of light and

"'Cotes, Lectures, .5. 187, 201-3.

w At Trinity College and in the university. Smith encouraged
science in a variety of ways. He not only published Cotes's works, he
gave the college money to erect a monument to Cotes, which carried
an epithet by Bcntley, and he gave the college library a bust of
Cotes. Later Smith presented the college w ith the statue of New ton
by Roubiliac. He completed the observ atory Cotes had begun. He
left a huge benefaction to the college, the university, and to science,
which included funds for his own Plumian Professorship. He set up
annual pri/.es to go to the two commencing bachelors of arts w ho had
done the most promising work in mathematics and natural
philosophy. These so-named Smith's Prizes were later used to
encourage work on parts of higher mathematics not appearing in the
examinations; they promoted distinguished mathematical work at
Cambridge. "Smith. Robert." D.XH 18:517-19. VVinstanley,
Unreformed Cambridge, 150. Gunther, Cambridge Science, 61. Rouse
Hall. History, 1 >1. Monk, Life of Bcntley 2:168. Willis and Clark.
Architectural History of the University of Cambridge 2:600. Richard
W atson. Anecdotes of the Life of Richard Watson, Bishop of Landaff . . .,
2d ed., vol. 1 (London, 1818), 14. In 1758 Lyons dedicated to Smith
his Treatise on Fluxions, which was used in teaching at Cambridge
alongside texts on the same subject by Newton, Saunderson, and others.

" 5 Robcrt Smith. A Compleat System of Optirks in Tour Hooks, viz .1
Popular, a Mathematical, a Mechanical, and a Philosophical Treatise. To
Which Are Added Remarks upon the Whole, 2 vols. (Cambridge, 1738).
The 340 subscribers included members of Lord Charles Cavendish's
mathematical circle, such as Macclesfield. De Moivre. and Folkes
(who subscribed for twelve copies); Cambridge mathematicians and
physical scientists, such as John Colson. Roger Long, Nicholas
Saunderson, Charles Mason, John Rowning, and Richard Davics;
Scottish professors of mathematics and physical science, such as
Colin Maclaurin, Robert Simpson, John Stewart, and Robert Dick;
and London instrument-makers, such as Ceorge Craham, James
Short, and Jonathan Sissons. Ten years before its publication, in
1728, Smith first advertised for subscribers for his optical treatise,
and if that was when Cavendish subscribed, it was the year he-
entered the Royal Society. He paid thirty shillings each for the two
volumes of the book. Alice Nell Walters. "Tools of Enlightenment:
The Material Culture of Science in Eighteenth-Century England"
(Ph.D. diss., University of California at Berkeley, 1992). 7.

W 'K. W. Morse. "Smith, Robert," DSB 12:477-78. Smith's book
was influential not only in Britain but abroad as well, where it was
translated into German. Dutch, and French.

Education of Henry Cavendish

matter, accompanied by explanations that often
lacked the conclusiveness expected of textbooks.
Moreover, the treatise ended by raising questions
and by suggesting not always consistent answers.
As the reader progressed through Newton's
account, the subject of optics widened rather than
closed in on itself as a body of knowledge suitably
prepared for learners.

By contrast, Smith's book on optics was a
proper textbook, an example of Cambridge science
teaching at its best, insofar as that teaching can be
conveyed by a book. Smith gave a selective ac-
count of Newton's optics, overlooking Newton's
second thoughts and hesitations, omitting what did
not fit. He cited and quoted Newton's queries
where they supported his system, ignoring their
grammatical form and treating them as if they were
assertions not questions.

Since Smith's purpose was to present optics
as & system, he could not leave undecided the nature
of light. On this question, he followed Newton but
was more decisive than Newton had been.
Although Newton was inclined toward the corpus-
cular view of light, he speculated freely on
alternative, or supplementary, etherial forms of
explanation. Smith acknowledged that Newton's
ether could explain the phenomena of light equally
well, but he used only Newton's streaming cor-
puscles and the intense forces with which they and
the corpuscles of bodies interacted at intimate
distances. In this interpretation, he had plenty of
support, for by the second decade of the eigh-
teenth century, the corpuscular theory of light was
widely subscribed to in principle. Because Smith's
System of Optirks came to be recognized as the main
authority on Newtonian optics after Newton's own
Optirks, in some respects supplanting it, it further
entrenched the corpuscular theory as the dominant
theory of light in eighteenth-century Britain.* 7
Cavendish subscribed to the corpuscular theory; in
all of his writings, published and unpublished, he
never used the word that characterized the alter-
native theory, "ether."

Smith illustrated the indispensable role of
instruments in optics by giving a history of
astronomy, which he began with Galileo, from
whom astronomy acquired its essential, modern
instrument, the telescope, and he brought the
history down to Bradley's great discoveries inci-
dental to his work on the cosmological problem

(the occasion for Lord Charles Cavendish's first
recorded scientific observations). He told of the
excellent London scientific instrument-makers,
such as George Graham, a man of "extraordinary
skill," whose help he had solicited in writing this
book* 8 . Smith included papers on refracting teles-
copes by Huygens and by his friend the astronomer
Samuel Molyneux.*'' Smith gave over an entire
chapter to Huygens's long, highly magnifying
refracting telescopes, including his 123-foot teles-
cope, which Huygens gave to the Royal Society,
and which Henry Cavendish later borrowed and
erected at his house. Smith treated the human eye
as an optical instrument, constructing a "tolerable
eye" from two hemispheres filled with water. 1 " 1 He
appended an essay on indistinct vision by his
friend and colleague at Trinity, the Bentley protege
James Jurin; 41 Jurin made scientifically precise the
imprecision of the senses, the ultimate source of
knowledge of the external world. Indistinct vision
was of great interest to Henry Cavendish, as we
will see.

Smith's presentation of optics was compre-
hensive. Not only were theory, mathematics,
experiments, and the construction and use of
instruments included, but so was the theory of
knowledge. In discussing how we come by our
ideas of things by sight, he took up the question
Molyneux asked of Locke. Would a blind man who
suddenly regained his sight be able to distinguish a
globe from a cube by sight alone? To this question,
the philosophers had answered in the negative and
were apparently confirmed by the recent experi-
ence of just such a man reported in the Philosophical
Transartiotts. This man did not know the shape of
anything by sight; he did not know how to move

"Authors in the first half of the eighteenth century in Britain
who held a corpuscular view of light arc identified in I lenrv John
Steffans, The Development of Sea-toman Optics in England (New York:
Science History Publications, 1977), 48, SO. 53; (i. N. Cantor, Optics
after Xevton: Theories of Light in Britain anil Ireland, 1704-1X40
(Manchester: Manchester University I'rcss. 1983), 32^33.

""Smith, Optirks, 332.

"''Smith, like Bradley, was a collaborator of Molyneux, When
Molyneux was appointed to the admiralty, he gave Smith his papers
and access to his house, which was fitted out with a complete set of
instruments. The plan was for Smith to complete Molyneux's work
on perfecting the methods of telescope-making. Molyneux died soon
after his appointment. Smith did the next best thing by publishing
Molyneux's papers in his book on optics. Smith, Optirks, 281.

'"'Smith, Optirks, 25.

'"James Jurin, "An Kssay upon Distinct and Indistinct Vision."
on pp. 1 15-70 at the end of Smith's Optirks.

122

his eyes; and he thought that things touched his
eyes as things touched his skin. Smith was not
satisfied with this answer, since it overlooked the
human capacity to reason about experience and
compare experiences derived from our several
senses. Smith had a ready subject at hand, his col-
league the Lucasian professor, the blind mathe-
matician Nicholas Saunderson. W hen approached
on the subject by Smith, Saunderson agreed with
him that by "reason," the blind man upon
regaining his sight could tell the globe from the
cube.''-' The answer Smith and Saunderson gave to
the question about the blind man was an inference
from the experimental philosophy. In knowing the
world, experience is reflected upon by reason.

Smith published one other book while
Plumian professor, this one concerned with the
sense of hearing instead of sight. Harmonics, or the
Philosophy of Musical Sounds. As in optics, in music-
Smith set out to make a system and to do it within
the experimental philosophy. The book came out
in 1749, the year that Henry Cavendish entered
Cambridge, and given his interest in physics and
music, it is likely that he read it. Like his book on
optics, Smiths book on music was well received and
became a standard text; George Lewis Scott, one of
De Moivre's pupils, recommended it to Edward
Gibbon as "the principal book of the kind."'"

Like natural philosophy, music had recently
undergone great change. The monodic idea had
become well established, and with it came the
harmonic, as opposed to the contrapuntal, approach
to musical composition, with its emphasis on
chords and the modern notion of key. By the use of
a definite key and of modulation between keys,
unity could be achieved in long expressive
melodies, but there was a technical problem:
although the modulation between closely related
keys could be carried out satisfactorily, the same
could not be said of the modulation between
remoter keys, as demanded for greater contrast.
The first workable solution came with the
introduction of an octave scale of twelve tones, the
half steps of w hich were precisely equal. 94

These several, related innovations — the
sense of key, modulation between keys, and equal
temperament — made possible the extended musical
forms of the early eighteenth century. Robert
Smith enters musical history at this point; with his
Harmonics, he intended to provide a full under-

Cavendish

standing of temperament. Ancient musical theorists
such as Ptolemy considered only perfect conso-
nances, and the scales they built upon them
necessarily contained imperfect consonances, dis-
agreeable to the ear. By distributing the largest
imperfections in certain concords over the others,
the modern theorists improved upon, tempered,
the ancient scales, with the result that the imper-
fect concords were less offensive although there
were more of them. Smith did not adopt the well-
tempered scale, as promoted by Bach in the Well-
Tempered Clavichord but addressed the problem
starting with the "first principles of the science." He
redistributed the imperfections of the ancient scales
in such a way as to make the imperfect consonances
all equally "harmonious." For this "scientific
solution" of the artistic problem, Smith constructed
a theory of imperfect consonances, the first ever (his
acoustical version of indistinct vision in optics). 1 ' 5

As an experimental philosopher. Smith con-
firmed his mathematical theory by practice. One
experiment was done by the Cambridge organist,
another by the bass-viol-playing clockmaker, John
Harrison, (who, Smith digressed, as we do, if
encouraged would improve navigation "to as great
exactness, in all probability, as need be desired").
Musical instruments and scientific instruments
became one in Smith's investigation. His theory
required that instruments be modified, and to this
end he was helped by "two of the most ingenious
and learned gentlemen in this University," John
Michell, who would become a good friend of
Henry Cavendish, and William Ludlam, to whom
Lord Charles Cavendish would supply astronomical
calculations. % Smith's was an improvement over

■"Smith, Oplicks, 42—13, and "The Author's Remarks upon the
Whole," at the end of the book, on 28-29.

'"Robert Smith. Harmonics, or the Philosophy of Musical Sounds, 2d
ed. (Cambridge, 1759). first edition in 1749. "Smith." AS'// 12:477.
"Smith," DNB 18:519.

'''Donald N. Ferguson, A History of Musical Thought, 2d ed. (New
York and London: Appleton. Century, Crofts, 1935), 272-78.

"Smith's solution was based on an analysis of the musical
interval, a "quantity" terminated by a higher and a lower sound. To
be precise, the musical interval is proportional to the logarithm of the
ratio of the frcqencics of the terminal sounds, on which Smith cited
Cotes's Harmonia Mensurarvm. If the ratio of the frequencies of two
sounds is not perfect, the interval they define, and the consonance, is
called "imperfect" or "tempered." By using the idea of "arithmetical
mean," Smith built a system in which the imperfect consonances "at
a medium of one with another, shall be equally and the most
harmonious." Smith. Harmonia, v-vii, 5-6, 8-9, 123.

'"'Smith, Harmonics, ix-xiv, 123.

Education of Henry Cavendish

123

other systems of temperament, but in the end the
modification of instruments it called for made
it impractical.

For many reasons it is understandable that
the Cambridge natural philosopher Smith should
write a scientific treatise on music. To start with, he
loved music and was expert on the violin-cello, and
his friends included musically talented scientific
colleagues, who encouraged his interest and
assisted him. He and his colleagues, after all,
belonged to a tradition of musical scientists going
back to Pythagoras and coming down to Huygens
and Newton. The tradition of the university too
worked in favor of this combination of interests:
music had been grouped with astronomy and the
parts of mathematics in the quadrivium, and there
was much that was still medieval about Cambridge.
Smith's Harmonics is filled with early writings on
music, often quoted at length in Latin and Greek,
and this too reflected the university with its empha-
sis on mathematics and the classics. 97

In the ancient world, musicians no doubt
followed their ear rather than the "theories of
philosophers," Smith said, arriving at temperament
"before the reason of it was discovered, and the
method and measure of it was reduced to regular
theory." But the ear was no longer sufficient, and
the theory was insufficient too, which was Smith's
starting point. Smith had a musical ear, but he did
not need one in harmonics; he had to have only
scientific theory, as he explained: a person without a
musical ear could tune an organ to any temperament
and to "any desired degree of exactness, far
beyond what the finest ear unassisted by theory
can possibly attain to." It was the same thing in
optics: Smith's colleague the blind mathematician
Saunderson taught Newton's theory of colors. 98

Finally, we recall, Smith lived in the age of
enlightenment, an image derived from sight but
which referred generally to a felt need for clarity.
Like musicians of "delicate ear," in listening to a
performance, Smith preferred to listen to a single-
string rather than unisons, octaves, and multiple-
part music. This he called a preference for
"distinctness and clearness, spirit and duration"
over "beating and jarring" and "confused noise."
When he listened, for instance, to a harpsichord, he
heard only single strings instead of the multiplicity
of strings that most people heard. He quoted from
his other book, System of Opticks, from Jurin's

account there of what happens when a person
comes out of a strong light into a closed room: at
first the room appears dark, but in time the eye
accommodates to the darkness and the room
appears light. Jurin's observation applied to sounds
too. The discernment of clarity within a confusion
of sound and the recovery of vision in darkness
symbolized the natural philosopher's quest. In his
primary capacity as a teacher of science. Smith was
provided with an implicit image by his music.
Musicians at first disliked Smith's retimed organ
despite its improved harmony, but musicians, like
scientists, could be educated; when the musicians
persisted, in time they could no longer stand the
"coarse harmony" of organs tuned the old way.
Smith's esthetics was an esthetics understood, which
meant by mathematics and experiment. 91 '

Robert Smith was the complete natural
philosopher, designer of instruments, experimenter,
and mathematical theorist. Of all the persons
teaching scientific subjects at Cambridge, with the
exception of John Michell, he was closest to the
kind of scientist Cavendish would become. We
would like to think that Cavendish became
acquainted with Smith at Cambridge, but that
event seems unlikely They were not in the same
college, and Smith probably did not lecture then
and was ill and reclusive. 100 It is, however, virtually
certain that Cavendish knew Smith through his
books on optics and music. Cavendish's theoretical
views on optics were the same as Smith's, and, as we

'"As in his book on optics, in his Harmonics Smith accorded
Huygens a prominent place, referring often to his Harmonic Cycle, in
which Huygens divided the octave into thirty-one equal intervals.
Huygens assumed that mean tones provide the best system, but he
erred. Smith said, in assuming that equal temperaments make all
tones equally disagteeable. In the course of his book. Smith cited
many scientific as well as musical authors on tempered musical
systems, such as the mathematicians John Wallis, Cotes, and
Leonhard Euler. He cited many works of science: Newton's Principia
on the nature of air pulses constituting sound and on the velocity of
sound, and Newton's Opticks on Newton's "happily discovered"
proportionality between the breadths of the primary colors in the
sun's spectrum and the differences of lengths of musical strings:
Cotes's Lectures upon Hydrostatics and Pneumatics on the expansion of
air with heat; De Moivre's Doctrine of Chances for the number of
permutations of the elements of a system of sounds; and Golin
Maclaurin's Fluxions. He cited the mathematician Brook Taylor, an
associate of Newton, with whom Taylor had planed to write a work
on music, and Jurin and Saunderson and other now familiar names.
Phillip S. Jones, "Taylor, Brook," DSB 13:265-6o\ on 265. Smith,
Harmonics. H. 25-2", 44, 100, 22H, 230.

■•"Smith, Opticks. ix, 33-35.

'"Ibid.. 171-72,210.

""'"Smith," DNB 18:518.

124

Cavendish

discuss later in this chapter, Cavendish was draw n
to music.

Smith's professorship was designated for
astronomy as well as for experimental philosophy,
but Cambridge acquired another professorship for
astronomy all the same, this one joining astronomy
to mathematics, specifically to geometry, which
made equally good sense. (Neither Smith nor his
predecessor Cotes was an astronomer, though they
did improve practical astronomy at Cambridge by
building the Trinity observatory.) Thomas Lowndes
left funds for establishing a salaried professorship
of astronomy and geometry, an important recogni-
tion of astronomy at Cambridge during the time
Cavendish was there. In 1750 Roger Long, a
graduate, then fellow, and since 1733 master of
Pembroke Hall, was named the first Lowndean
professor. Long was an eccentric character, a tory in
a predominantly whig Cambridge, an autocrat
constitutionally destined to be at cross purposes
with the people around him, constantly feuding
with the fellows of his college, especially over the
right of veto, which he exercised with willful
frequency. Like his Plumian colleague. Smith,
Long was a skillful musician, who presented the
king and queen w ith a musical instrument of his
own inv ention, the "lyrichord." Long was renowned
as an inv entor of fantastic machines in his scientific-
field, astronomy, immense, dramatic things never
before seen in Cambridge, which actually served
the purposes of education. Some of these Long
described in his Astronomy, a standard text in the
university when Cavendish arrived there. The
frontispiece of the first volume illustrates an early
construction, a glass celestial sphere known to a
"great number of people" and. Long complained,
imperfectly copied by several. The book describes
another of his machines, a narrow ring twenty feet
across on which the constellations of the zodiac and
the ecliptic were inscribed. The viewer, who sat in
the middle, was treated to a panoramic view of this
bit of the heav ens. Long w rote of his w ish to build
the ultimate apparatus, a "planetarium," which
would rotate around a platform of spectators. He
later built and installed at Pembroke the famous
"great sphere," a revolving globe eighteen feet
across, capable of holding thirty people. Designated
the "Cranium," this consummate lecturer's plan-
etarium prov ided the frontispiece of the second
volume of Long's Astronomy. Long had an excellent

assistant, — formerly Long's footboy — Richard
Dunthorne, w ho held the butlership at Pembroke,
and who published a number of books and papers
on the motions of the moon, comets, and the
satellites of Jupiter; he promoted the building of an
observatory over the gate of another college, St.
John's, w hich he used to derive his lunar tables; this
versatile astronomer also superintended the draining
of the fens for the Bedford Level Corporation.""
Long's own contribution to astronomy in Cambridge
in Cavendish's time was his teaching, and his
lecture-text was his main publication. 10 -'

In Astronomy Long used mathematics
sparingly, but he was emphatic on the point that
astronomy was a quantitative science, in observation
and in theory, and his account of astronomy
accordingly began with the subject of quantity in
all of its manifestations in astronomy. His
descriptive treatment of astronomy was, like his
machines, grand if not grandiose; in contrast to the
usual perfunctory single chapter on the fixed stars,
his book devoted many chapters to their immense
distances and so on. He placed astronomy within
natural philosophy, the study of the bodies that
comprise the universe. Since the gravitational force
was known but the forces of light, magnetism, and
electricity were not, gravitational astronomy was far
more advanced than the other parts of natural
philosophy. Newton's Principia "gave an entirely

""Wordsworth, Schotat Academicae, 249. "Dunthorne. Richard,"
DNB (r. 235-36.

"'-'The first volume of Long's Astronomy. Iii Five Hoots was
published in Cambridge in 1742. The second volume did not appear
until twenty-two years later, in 1764, for reasons "it would be of no
service to the public to be informed." These reasons had in part to
do with his interest in music, as a letter from Cambridge noted: "Dr.
Long advances, but slowly, in his astronomical work; tho' y* larger
part of his 2d vol. is I believe printed. But he keeps amusing
himself. . . with alterations in musical instruments, of W* he is very
fond . . ." J. Green to Thomas Birch. 24 Jan. 1 760, BL Add Mss 4308,
ff. 192-93. Instead of an apology. Long gave his readers accounts of
notable work in astronomy carried out since he began his text; e.g.,
Bradley's discovery of the aberration of light, the French
measurements of the length of a degree to determine the shape of
the earth, and observations of the 1761 transit of Venus across the
sun. Only in 1 7X4. after Long's death, was the remaining part of the
book published. Long. Astronomy l:ix-x, and 2;iii. "Long, Roger,"
DSli 12:109. Rouse Ball. History, 105. Gunther, Early Science in
Cambridge . ln4-67. Ketton-Cremer, Gray, H3-X4. Long did do some
observational astronomy, in which he was attracted to the great
questions of the science, such as the distance of the fixed stars and
their possible motion, concluding after "long and careful enquiry,"
but incorrectly as it happened, that stars do not move. He knew the
active astronomers, such as Bradley, under whose vertical telescope-
he lay with his head on a cushion. Long. Astronomy. 2:637-38.

Education of Henry Cavendish

new face to theoretical astronomy"; it had heen
"raised, at once, to a greater degree of perfection
than could have been hoped for from the united
labours of the most learned men, for many ages, by
the amazing genius of one man — the immortal
NewtonV m The great instrument-makers, especially
the British, supplied the observers who kept astron-
omy advancing after Newton. Because Lord ("hades
Cavendish was a subscriber to Long's Astronomy,
Henry Cavendish is certain to have seen it at home
if not at Cambridge, and he might have attended
the flamboyant lectures on which it was based. After
Cambridge, Cavendish built his own observatory,
where he studied the heavens for the rest of his life.

At Cambridge, where religion and
Newtonianism had formed an alliance, we find the
regius professor of divinity, Thomas Rutherforth,
teaching Newtonian natural philosophy and
publishing on it as well as on religion, and using his
membership in the Royal Society to promote sales
of his books. 104 In 1748, the year before Cavendish
entered Cambridge, Rutherforth published the
lectures he gave at St. John's College, A System of
Natural P/iilosop/iy. m Cod's presence was taken for
granted; the divinity professor presented natural
philosophy as subject to be studied entirely within
its own scientific terms. Throughout his lectures
Rutherforth used geometrical arguments, even
managing to convey a notion of infinitesimal reason-
ing while at the same time not assuming the most
rudimentary knowledge of quantity (he explained
that a fraction decreases as its denominator in-
creases 10 ''). He had an engaging, self-deprecating
honesty, asking forgiveness for the errors and in-
exactitude in his efforts to communicate to persons
unfamiliar with the profounder parts of mathe-
matics. 107 Being no particular expert himself, he-
gave the impression that he was writing for persons
not much below his own level of understanding.
Wordy, full of asides and sarcasms, Rutherforth's
text reads like the spoken popular lectures they
were. It was not one of the best elementary texts
on Newtonian natural philosophy, but it was
competent at the level of its intended audience. 108
Its list of subscribers is long, numbering about a
thousand, of whom about a third are identified
with Cambridge. (That Lord Charles Cavendish
did not subscribe to this book does not surprise us.)
The text and its local support are testimony of the
prestige of Newtonianism at Cambridge, and

125

according to William Heberden, it furthered the
cause by stimulating lectures on science within
other colleges at Cambridge. 109

For completeness, we should point out that
when Cavendish was at Cambridge, the Jacksonian
professorship of natural philosophy had not yet
been established. The Woodwardian professor of
geology, Charles Mason (not the Charles Mason of
the Mason-Dixon line, whom we will meet later),
was a Fellow of the Royal Society and took an
interest in a miscellany of scientific questions, but he
would not have contributed in any way to Cavendish's
education. 110 The professorship of chemistry was held
by John Mickleborough, who like his predecessor
Vigani was an ardent advocate of Newtonian
chemistry. Twenty-five years before Cavendish
became a student, Mickleborough could excuse his
delay in answering letters on the grounds that he was
"now engaged in a course of Chemistry here, I can
think of no things but calcinations, sublimations,
distillations, precipitations, etc." but after 1741 he
evidently did no more lecturing on chemistry, and
neither did anyone else (to our knowledge) until
after Cavendish had left Cambridge. 1,1

Before we leave the subject of the contri-
bution of Cambridge to Henry Cavendish's educa-

IM Long, Astronomy 2:7 1 7-18.

104 Thomas Rutherforth to Thomas Birch, 30 Jan. and 6 Feb.
1 742/43, BL Add Mss 4317, ff. 305-6, 308.

""Thomas Rutherforth, A System of Natural Philosophy, lieing n
Course of lectures in Mechanics, Optics. Hydrostatics, and Astronomy:
Which Are Read in St. Johns College Cambridge, 2 vols. (Cambridge,
1748). "Rutherforth, Thomas," DNB 17:499-500.

■"■Ibid.. 23.

""Ibid., 199.

""Robert K Schofield, Mechanism and Materialism: British Natural
Philosophy in an Age of Reason (Princeton: Princeton I nivcrsity Press.
1970), 97.

""Heberden had been a colleague of Rutherforth at St. John's.
He later recalled that in his student days at Cambridge, around 1730,
Professor Saunderson had lectured on Newton, geometry, and
algebra while the college lecturers largely ignored these subjects.
"The works however of I)r Smith and I)r Rutherford naturally
introduced a greater attention to the subjects of which they treated
in the two great colleges," Trinity and St John's; the teaching spread
from these to other colleges. Christopher Wordsworth. Scholar
Aradrmicae: Some Account of the Studies at the English I'niirrsitirs in the
Eighteenth Centun (Cambridge, 1877), 66-67.

""Indicative of Mason's range of interests and of his few papers
in the Philosophical Transactions arc the "hints" about melting iron
and about a burning well in a letter he sent to the president of the
Royal Society at about the time Cavendish entered Cambridge:
Charles Mason to Martin Koikes, 22 Jan. 1746/47, Wellcome
Institute, Martin Koikes Papers. Ms. 5403.

11 'John Mickleburgh to Dean Moss in 1725. in Nichols. Literary
Illustrations 4:520. Wordsworth, Scholar Aiademirae. 188-89. L. J. M.
Coleby, "John Mickelburgh. Professor of Chemistry in the I 'niversity
( »f ( lambridge, 1 7 1 8-56," Annals of Science 8 (1952): 1 65-74.

126

Cavendish

tion in science, we return briefly to John Colson.
I le probably did not lecture, but he went to a great
deal of trouble to see that good scientific and
mathematical texts were available to students.
After becoming Lucasian professor, he translated
into Knglish several books from several languages,
which included Peter van Musschenbroek's Elements
of Natural Philosophy, the subtitle of which is Chiefly
Intended for the Use of Students in Universities The
reason Colson gave for making this translation was
that there was a need for a "system" of natural
philosophy in Knglish (Musschenbroek used that
word himself), and he thought that Musschenbroek's
was the best. Musschenbroek drew on Continental
sources such as Descartes and Leibniz, (concerning
whom Colson had a bone to pick with Musschen-
broek), but the principal source he made clear: he
embraced the "very many and great discoveries of
the illustrious Newton (the glory of England, to
whom no age has produced an equal)." 113

Colson recognized a kindred spirit in
Musschenbroek, who at the time of Colson's
translation was professor of mathematics and
astronomy at the University of Leyden, and whose
main publications were extensions of his lectures
in ever larger books. His predecessor at Leyden
had been Willem Jacob 'sGravesande, another
systematizer and writer of textbooks whose famous
Mathematical Elements of Natural Philosophy,
Confirmed by Experiments: or, an Introduction to Sir
Isaac Newton's Philosophy had been translated from
the Latin into Knglish by J. T. Desaguliers, in
1720-21. Musschenbroek and 'sGravesandc had
both studied at the University of Leyden when its
most successful teacher Hermann Boerhaave was
lecturing there. These three professors made
Leyden the capital of Newtonianism on the
Continent, and they did so not through their
research, which was minimal, but through their
teaching, which was ample. Kxperiment had
replaced stable certainty with ceaseless change,
they said, and they encouraged their students to
discover using the experimental way to truth. In
his textbook, Musschenbroek said that the person
who solved the problem of electricity would have
his name struck on public monuments. 114 When
Cavendish was a student, Leyden was probably a
better place to learn natural philosophy than
Cambridge, but it was not necessary to be in
Leyden to learn from it. Texts by Musschenbroek,

'sGravesande, and Boerhaave were recommended
reading at Cambridge, and texts by British writers
were strongly influenced by them." 5 In both uni-
versities the emphasis was on Newtonian philosophy,
and in both the professors were primarily teachers
and not researchers. Colson, Smith, and Long may
not have been as influential in their teaching as
Musschenbroek, but they regarded their work in
much the same way. For an avaricious and
perceptive reader like Cavendish, the experimental
approach of the Leyden authors supplemented the
mathematical emphasis at Cambridge, and there
would have seemed no contradiction; 'sGravesande,
for example, taught by the experimental method,
but he believed that mathematics was the true
foundation of natural philosophy.

In broad outline we have sketched the
scientific tradition at Cambridge insofar as it was
represented by the texts of its early and mid
eighteenth-century professors. When Cavendish
entered the ranks of scientific researchers, he was a
master of mathematical methods and concepts of
science within a certain New tonian framework, and
the connections between this framework and
Cambridge education are many, significant, and
unlikely to be mere coincidence.

Giardini Academy

If there was a musical influence on Henry
Cavendish, it came from his mother's side of the
family. The duke and first duchess of Kent had a
love of music, and the duke, we may recall,
combined this interest with his political career
when as lord chamberlain he worked to bring
Italian opera to London. Later, in 1719, the duke
was one of the original subscribers to the Royal
Academy of Music, and he (but not the duke of

"'From the Latin Colson translated Pctrus van
Musschenbroek's Elements of Natural Philosophy in 1744; from the
French he translated Jean Antoine N'ollet's lectures in Experimental
Philosophy in 1748; from the Italian he translated Maria (Jaetana
Agnesi's Analytical Institutions in 1801; and he edited the 3d edition
of Brook Taylor's Linear Perspective, or a New Method of Representing
Justly Ml Manner of Objects as They Appear to the Eye in 174°. We have-
already diseussed his translation from the Latin of Newton's Method
of Fluxions.

" 'Preface and translator's advertisement in Musschenbroek,
Elements of Natural Philosophy, v. xi.

" 4 Edward (i. Ruestow, Physics tit Seventeenth unci Eighteenth-
Century Leiden: Philosophy mid the New Science in the University (The
Hague: Martinus Nijhoff, 1973), 7-8, 1 15-21, 135-39.

" 5 D. J. Struik. "Musschenbroek, I'ctrns van." DSH 9:594-97. A.
Rupert Hall. "'sGravesande, Willem Jacob," DSB 5:509-11.

Copy nghted m aerial

Education of Henry Cavendish

Devonshire) beeame one of its twenty directors. 1 16
There is a painting of the Kent family showing
them being musically entertained, 117 and we know-
that the Yorkes and the Greys often attended
concerts at the Rotunda. 1 1K Had Henry Cavendish
shown any musical interest, he would surely have
been encouraged. Many of his future scientific
colleagues were accomplished musicians, as we
have suggested in our discussion of science at
Cambridge. In describing a "water-worm" that
propagated after being cut to pieces, the French
scientist Rene Antoine Reaumur said the worm
was "of the Thickness of the Treble String of a
Violin," a remark which suggests an intimate
knowledge of music and its instruments in the
eighteenth century, since lost. 119

Evidence of Henry Cavendish's interest in
music is sketchy. There is a mathematical study by
him, "On Musical Intervals." 120 There is a reference
to a musical event in, of all places, Cavendish's
laboratory notes on pneumatic chemistry: in 1782
he used his eudiometer — the instrument for
measuring the "goodness" of air — to compare the
good air of Hampstead, one of the benefits of
Hampstead, to which Cavendish had just moved,
to the used "Air from Oratorio." 121 The auction
catalogue of the contents of Cavendish's house at
Clapham Common at the time of his death, listed a
grand piano. 122 According to a story that on face
value seems unlikely but which probably contains
a core of truth, Cavendish came together with
Michell, Herschel, Priestley, and others over
musical entertainment. 12i

Given the limited evidence, in this dis-
cussion (as in the discussion of De Moivre), we
proceed tentatively. The name Henry Cavendish
appears on a list of subscribers to the musical
academy of Felice de Giardini, and we think that
this Henry Cavendish is our subject. Giardini, a
musical entrepreneur, moved from Italy to England
in 1750, and for ten years beginning in 1755 he
adapted Italian operas for the King's Theatre.
Later he composed quartets and concertos for
strings and even a successful English oratorio, Ruth.
Like Lord Charles Cavendish, Giardini was a
governor of the Foundling Hospital, where Handel
gave concerts; and in 1774 Giardini proposed
establishing a musical academy in the Hospital. By
the time Cavendish was (if we are right) in contact
with him, Giardini was the preeminent violinist in

127

London. 124 Johnson sympathized with Giardini
when he learned that the man did not make more
than seven hundred pounds a year despite his
superior ability. 125 To do even this well, Giardini
had to combine activities, and one way he did was
by running an academy by subscription on the side.
In 1758 or 1759, Henry Cavendish along with
sixteen others agreed to continue to meet as an
"academy" in the coming year as they had in the
last, only under new terms, obviously having to do
with Giardini's finances. The members of the
academy agreed to pay eight pounds, half up front
and the rest when the academy had met twenty
times. The academy seems to have met weekly. It
would be up to the subscribers if they were to
meet in the morning or the evening; if in the
morning, as they had been meeting, breakfast
would be provided, if in the evening, lighting. 12,>
Thirteen of the seventeen, including Cavendish,
had already paid their advance, and if all paid up,
Giardini would have earned around one hundred

"'•Otto Krich Deutsch, Handel: A Documentary Biography (New
York: DaCapo Press, 1974), 91, 102.

"illustration 1. in Joyce Godber, Hie Marchioness Grey of Wrest
Park, vol. 47 of the Publications of the Bedfordshire Historical
Record Society, published by the Society, 1968.

» 8 Gunther, Birch, 62. Great Britain, Historical Manuscripts
Commission, Report on de Manuscripts of the Rail of Egmont. Diary of
Viscount Perckal Afterwards hirst Earl of Egmont, vol. 1: I7.i0-I7.l1
(London: His Majesty's Stationary Office, 1920). 93, 227; vol. 2:
1734-1 738 (London: His Majesty's Stationary Office, 1923), 30.

"''Rene Antoine Reaumur, "An Abstract of What Is Contained
in the Preface to the Sixth Volume of Mons Reaumur's History of
Insects . . ." PT 42 (1742/43): xii-xvii, on xv.

'-"Cavendish Mss VI(a), 28.

'-'This entry is unclear as to Cavendish's part. It begins with a
comparison of "air caught by /the instrument-maker Edward/ Nairne
in 2d gallery of Drury Lane playhouse Mar. IS 1782 with air of
Hampstead of Mar. 16." It follows with "Air from Oratorio about
same time." The oratorio may have been attended at Drury Lane by
Nairne, or it may be a separate source of air collected by Cavendish
at about the same time. "Experiments on Airs." Cavendish Mss II,
5:189.

,22 /t Catalogue of an Assortment of Modern Household Furniture. . .
the Genuine Property of a Professional Gentleman Which Will lie Sold by
Auction fa Mr. Squibb, at His Great Room, Saville Passage, Sazille Row,
on Wednesday. December 5, 1810, and Two f ollowing Days, at Twelve
O'Cloclt. Item 45 is a grand piano-forte, by Longman and Broderip. in

a mahogany case.

'-'"Michell, John," DNB 13:553-34. on 555.

'- 4 R. H. Nichols and F. A. Wray, The History of the Foundling
Hospital (London: Oxford University Press, 1935), 247. Roger Fiske,
English Theatre Musir in the Eighteenth Century (London: Oxford
University Press, 1973), 284, 286.

'"Johnson's exchange with Goldsmith on this point is quoted in
Fiske. English Theatre Musir, 285.

126 Great Britain. Historical Manuscripts Commission, Report on
Manuscripts in Various Collections, vol. 8: The Manuscripts of the Hon.
Frederick Lindley Wood; M. /.. S. Clements, Esq.; S. Philip Vnwin, Esq.
(London: His Majesty's Stationery Office. 1913), 188-89.

128

and thirty-five pounds, less out-of-pocket
expenses, a good installment on his seven hundred
or so pounds for the year.

The subscribers were young persons of
both sexes, two of them relatives of Cavendish,
George Manners and Lady Granby (Frances
Manners). One subscriber was Cavendish's almost
exact contemporary William Hamilton, 1:7 who is
popularly know n as the husband of Lord Nelson's
mistress Km ma but who is also known as a solid
diplomat and a good student of volcanoes. In 1794
Sir Joseph Banks w rote to Sir William Hamilton in
Naples to compliment him on his description of
the recent eruption of Vesuvius. Everyone at the
Royal Society thought it was excellent: "Cavendish
in particular who you know is little given to talking
& not at all to flattery says it is very valuable
addition to the theory of volcanoes & that tho he

Cavendish

does not on any account w ish to derogate from the
merit of your former papers this is certainly the
most valuable one we have receive! from you." 128
Just w hat transpired twenty-fiv e years earlier when
Hamilton and Cavendish were in Giardini's
academy is unclear, but it undoubtedly had to do
vv ith listening together.'-"'

1 I lamilton has helped us date the agreement between Giardini
and the subscribers to his academy. By our reckoning, it was made
after Hamilton's marriage in 17.SKand before December 1759.

'-'"Sir Joseph Banks to Sir William Hamilton. 30 Nov. 17 l M.
BL,.Egcrton Ms. 2641, pp. 155-56.

'-"'In Italy a private concert In dilettantes was called an
"accademia." which may have been Giardini's meaning. This
information is given in a work from the time, Charles Burney, Present
Stair of Musk in France and Italy (London. 1771). quoted in Horace
Wa/po/e's Correspondence, vol. 18: With Sir Horace Mann, vol. 1. eds. W.
S. Lew is. W. 1 1. Smith, and G. L. Lam (New I laven: Mile I Iniversity
Press. 1954), 13, n. I6a.

Copyrighted m aerial

CHAPTER 2

^cience

Introduction to Scientific Society

Early in 1753 Henry came down from
Cambridge, and that summer he and his brother,
Frederick, went with their father to dinner at
Heberden's. The usual people were there. Birch,
Watson, Wray, Mann, and the many-sided physi-
cian and poet Mark Akenside, whom Lord Charles
had recommended for fellowship in the Royal
Society for his knowledge of natural philosophy. 1
Frederick, whose accident occurred the following
year, did not come to any more of these collegia!
dinners. Henry Cavendish came to twenty-six
dinners with his father in the ten years after
completing his studies at Cambridge. 2 By far the
most common location was Heberden's house,
though dinners often took place at Yorke's and
occasionally at Watson's, Stanhope's, Wray's, and
at Cavendish's own home.-' Lord Charles went to
lengths to ensure that Henry was known to his
scientific friends.

In 1760 Henry Cavendish entered the
Royal Society, where he spent the rest of his life as
an unsalaried, almost full-time servant. Evidently
he never considered a career in politics, even
though in aristocratic families, sons and even sons
of sons were practically duty-bound to enter the
House of Commons. 4 The aristocracy was then in
full flower in parliament: in 1760, the year George
III was crowned, the Commons had five Manners,
five Townshends, and four Cavendishes (including
Richard Chandler after marriage and a name
change). In not following this pattern, Henry
Cavendish had before him the example of his
father, whose public life was then devoted to
learned affairs. Twenty years earlier Lord Charles
Cavendish had left politics for a more fulfilling life
in science. Henry Cavendish would enter science
directly, and there he would experience an even
fuller life there than the one his father had known.
There is every reason to think his father backed
him all the way; indeed, he had paved the way.

It was common for Fellows of the Royal
Society to introduce their sons to the Society by
bringing them as guests. 5 Lord Charles brought
I lenry to his first meeting of the Royal Society, in
June 1758, by which time he had already
introduced Henry to the leaders of the Royal
Society at his many dinners. Henry came to
eighteen meetings of the Royal Society as a visitor,
the last in March 1760, and at fifteen of these
meetings he came as a guest of his father. He came
also as a guest of Birch, the friend of the family,
and of Peter Newcome, teacher at I lenry 's school
at Hackney/' The year before Lord Charles
Cavendish introduced Henry to the Royal Society,
he had received the Copley Medal, and as vice-
president, he presided over almost half of the meet-
ings to which he brought his son. Henry Cavendish
could feel reassured in this new public world of the
learned.

At a meeting Lord Charles Cavendish ab-
sented himself from, on 31 January 1760, Henry
Cavendish was proposed for membership in the
Royal Society. The original three proposers were
Willoughby, Macclesfield, and Bradley, and I leberden
wrote the certificate. Seven more Fellows of the
Royal Society signed the certificate during the

125 Aug. 1753, Thomas Birch. Diary, HI. Add Mss4478C, f. 2.V5.

-Again with the proviso that Birch also attended the dinners
Birch Diary, passim.

'Henry Cavendish came with his father to dinner at Heberden's
twelve times.

J L. B. Namier, The Structure of Politics tit the Accession of George III,
2 vols. (London: Macmillan. 1929) 1:5.

Examples from around this time: John Canton, jun., was a
guest of John Canton, and Johnathan Watson, jun., was a guest of
Johnathan Watson. Entries for 26 Mar. and 9 July 1767. Royal
Society. J B 26.

'•Royal Society, JB 2.5, 1757-60, passim. The third person to
invite Henry Cavendish to the Royal Society as a guest was Michael
Lort, an antiquarian, who in 1754 was appointed professor of Greek
at Cambridge. Since he was not yet himself a Fellow of the Royal
Society, he must have had the right to invite guests as a university
professor. Lort was a good friend of the Cavendish in-law Philip
Yorke, and he is also said to have been librarian to the duke of
Devonshire.

130

three months it was posted: in addition to Heber-
den, they were Wray, Bireh, Wilbraham, Hadley,
S(|iiire, and Watson, all, we note, members of Lord
Charles Cavendish's dining circle, with whom
Henry too had dined. With that endorsement, he-
was balloted and unanimously elected on 1 May
1760. The certificate read simply that Henry
Cavendish was worthy, "having a great regard for
Natural Knowledge, & being studious of its
improvement." 7 The generality of the endorsement
in this case was no doubt not an excuse, as it
sometimes was; we suspect that from the begin-
ning, Henry Cavendish's trademark was his knowl-
edge in all parts of natural philosophy.

Just as at the Royal Society, at the Royal
Society Club prospective members were custom-
arily brought as guests before they were elected
members. This was the case with Henry Cav-
endish, though he was proposed for, as opposed to
elected to, membership before he had actually
attended a dinner. There was no need for him to
make himself known to the members, since he
knew them already from his fathers dinners.
Those frequently attending were Watson, Birch,
Heberden. Knight, Willotighby, Davall, Squire,
Peter Newcome, Akenside, and the president of
the Royal Society, who also presided over the
dinners, Macclesfield. * Macclesfield recommended
1 lenry Cavendish for membership on 10 November
1757, at a dinner at which Lord Charles Cavendish
attended, which implied that his election was also a
virtual certainty. 1 ' Cavendish w as balloted according
to his place in line, a two-year wait as it turned out,
though that was a readily circumvented formality.
Cavendish was repeatedly invited to dinners as a
guest of his father and treated as if he were a
member from the time of his proposal. As it so
happened, the timing was perfect: he was elected
to membership in the Royal Society Dining Club
on 31 July 1760, two months after his election to
the Royal Society. Henry Cavendish was then
twenty-nine and certainly not a ward of his father;
he continued to accompany his father to the club,
but often he came on his own.

In 1760 Henry Cavendish also was elected
to the Society of Arts, where his father was an
active member. Henry was not active, but he kept
up his subscription and received the journal,
showing that much interest in the Society. 11 ' We
will return to his relative indifference to this

Cavendish

society later in this biography in connection with his
highly active membership in the Royal Institution.

It has been alleged that Henry Cavendish's
family was greatly disappointed that he did not
pursue an ordinary public career and that as a result
he was treated by his father in a niggardly fashion."
This speculation is plausible, but it also goes
against certain known facts. Chief among them is
that Lord Charles brought his son into his scientific
circle, and at an early age, as we have seen. Given
the harmony of interests of father and son, there is
good reason to think that Henry wished to live
with his father in the double house with separate
living quarters on Great Marlborough Street. Lord
Charles Cavendish, it would appear, raised his son
in the manner that was then becoming established
in England; that is, with respect for individual
autonomy and with a show of sympathetic
interest. 1 -' Henry was not coerced into attempting a
public life for which he was not suited but was
allowed to do what he wanted. As to the charge of
niggardliness, we have little evidence to go on. Since
Henry' did not marry, there was no subsequent set-
tlement, and we have nothing in writing between
him and his father. Thomas Thomson said that he
had an annuity of 500 pounds," which sounds right;
it was the annuity Lord Charles received from his
father at the time of his marriage. Since Henry lived
at home and did not gamble and carouse, he could
have managed comfortably with that income.

Science at the Royal Society

We turn to the public world of science for
Henry Cavendish's education in the practice of

"Royal Society, Certificates, vol 1, no. 10, f. 198.
"Royal Society Club, Minute Book, no. 4. 1 760-64, Royal
Society, passim.

''Archibald Geikie, Anna/s of the Royal Society Club (London:
Macmillan, 1917), 63.

"'On 9 January Henry Cavendish was proposed for membership
by Mr. Cosheap; he was elected at the next meeting, on 16 Jan. 1760.
Royal Society of Arts. Minutes, vol. 4. Henry Cavendish held no
office in the Society, did not publish in its journal, and. it seems, did
not belong to any of its committees. In 1786 he was summoned to
attend-hc did not attend-the Committee of Polite Arts to take part in
an educational experiment. I), fi. C. Allan, personal communication,
and.////. R.S.A., 1966, p. 1033, n. 11.

"George Wilson. The Life of the Honourable He/in Cavendish
(London, 1851), 161.

IJ Stone. family, 22, 151 Rudolph Trumbach, The Rise of the
Egalitarian Family: Aristocratic Kinship and Domestic Relations in
Eighteenth-Century England (New York: Academic Press, 1978), 292.

" Thomas Thomson, the History of Chemistry, vol. 1 (London.
1830). 336.

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Science

131

science, using as our source the papers appearing in
the Royal Society's Philosophical Transactions, which
came regularly into Lord Charles's house during
the years Henry was a student at Cambridge.
(When we say that Henry was a student at
Cambridge, we suppose that he was away from
home only during term, about six months out of
each year; for the rest of the year, he probably was
living with his father on Great Marlborough
Street.) Beginning in the year Henry came home
from Cambridge for good, Lord Charles was on the
committee that passed judgment on every paper
considered for publication in that journal.

Every issue of the Philosophical Transactions in
the middle of the eighteenth century was an expres-
sion of confidence in the experimental philosophy.
An account of an aurora borealis in that journal in
1750 makes the point: "The best description I can
give of it /an aurora seen in Norwich/ is, to liken it to
that light produced in a dark room, when one of the
seven original colours is separated from the rest, after
they have passed thro' a prism, and been collected
together again by a convex lens." 14 By this time the
direct experience of nature could be likened to an
experiment on nature, not the other way around.
The experiment was more familiar than nature.

The original strictures of the Royal Society
against inflated language in reporting scientific
findings were still professed. In an exchange of
letters in the Philosophical Transactions, the foreign
electrical experimenter George Matthias Bose
conceded that by his "style and expressions" he
had "embellished a little" the account of an
experiment. Watson, his correspondent, took Bose
to task: "The language of philosophers should not
be tainted with the licence of the poets; their aim
in the communicating their discoveries to the
world, should be simple truth without desiring to
exaggerate." The thing itself, nature, was cause
enough for "admiration." 15 Spare writing can have
an elegance and force of its own; Henry Cavendish
had a gift for this kind of writing, which was not a
small reason why he could make a life satisfactorily
within science. Not all contributors to the journal
wrote as plainly as he; descriptions of auroras, for
example, that filled the pages of the Philosophical
Transactions ty pically combined objective descriptions
with expressions of awe. We make the obvious
observation here that this journal does not read like
a scientific journal of today.

Most of the papers in the Philosophical
'Transactions were in English, though papers in
Latin from abroad were not uncommon and were
almost never translated, a reflection of British
education and the continuing use of Latin as a
universal language of scholars. All of the papers in
French, Spanish, and other modern European
languages were translated, again reflecting British
education and also British insularity. 16 Cavendish
read Latin and wrote it passably, and he also read
French, but that was about the extent of his
competence in languages. There were Fellows of
the Royal Society in London who could translate,
and Cavendish like most other readers of the
journal were in their debt.

Authors appearing in the Philosophical
Transactions were identified by profession and title,
if they had them, and sometimes by place. When
they were referred to, it was often as experts,
sometimes highly specialized ones, such as
"electrician," sometimes less specialized ones,
such as "chemist," and often very broad ones, such
as persons who pursued "natural history" and
"natural philosophy." Those interested in minerals
were likely to be called not "mineralogists" but
"naturalists" or "natural historians." These same
terms applied to persons interested in, say, stones
from a rhinoceros's stomach. "Philosopher" was an
all-purpose term for the learned. 17 "Natural philoso-
pher" was commoner. Cavendish is often called a
"chemist," but that is because he is discussed
primarily in connection with the chemical revo-
lution. In his day he was usually called a "natural
philosopher."

When Lord Charles Cavendish entered the
Royal Society in 1727, the year Newton died,
references to Newton in the Philosophical Trans-
actions were usually to praise. Twenty years later,
when Charles's son Henry was at college, refer-
ences to Newton were respectful but tempered

,4 Henry Baker, "A Letter . . . Containing Abstracts of Several
Observations of Aurorae Borcales Lately Seen," FT 46 (1750):
499-505, on 501.

'"•William Watson, "A Letter . . . Declaring That He as Well as
Many Others Have Not Been Able to Make Odours Pass Thro' Glass
by Means of Electricity . . .," PT 46 (1749/50): 348-56, on 355-56.

"■There is one exception. A paper sent to the instrument-maker
James Short was translated from the Latin: Joseph Steplin, "An
Account of an Extraordinary Alteration in the Baths of Toplitz in
Bohemia . . .," />7'49 (1755): 395-96.

"/T 46 (1750): 1 18, 126. 250-5, 362, 369, 589. and passim.

Cavendish

and occasionally critical. The author of a paper on
tides said that Newton had discovered the cause of
tides, hut because tides were so complex they still
had to be observed. 18 Great as he was, Newton had
not done everything. Thomas Simpson, mathe-
matics teacher at the Royal Military Academy at
Woolwich and the principal contributor of math-
ematics to the Philosophical Transactions, solved a
problem in inverse fluxions (integration); conscious
that his solution differed from Newton's, Simpson
said that it was "impossible to disagree without
being under some apprehensions of a mistake."' 1 '
In this case: Newton was great, but he made mis-
takes. If foreigners pointed out Newton's mistakes,
it was a different matter; like the Italian who
claimed he had discovered six errors in Newton's
Prindpia, they would be attacked by the home
guard.-'" Alexis Claude Clairaut, who had argued
that Newton's inverse-square law of gravitation was
inexact, made a public retraction, but that did not
spare him. Having detected an absurdity in
Clairaut's reasoning, Patrick Murdock wrote a
paper to dispel the erroneous view that Newton's
propositions on the moon's motions were "mere
mathematical fictions, not applicable to nature"; on
the contrary, Murdock said, Newton's work was
"fully confirmed and verified." 21 Clairaut wrote a
kind of apology for the Philosophical Transactions, in
which he said that he had not intended to
disparage Newton. Newton had not thought it
impossible to be "opposed by experience," but in
their zeal some people did not distinguish
"betw een the different ways of opposing that great
man's sentiments," but still, if the Royal Society
wished, Clairaut would reword his disagreement
with Newton. 2 - (The disagreement hinged on
assumptions about the density of the earth, and
Clairaut's book on the figure of the earth stimulated
Henry Cavendish's lifelong interest in the density
of the earth.) Criticism of Newton was a touchy
matter. Euler too had once believed that Newton's
theory conflicted with observations of the motion
of the moon but he did no longer; Clairaut's
retracted claim, he said, had not been damaging
but on the contrary had given "quite a new lustre
to the theory of the great Newton."-'

Kuler did, however, have a quarrel with
New ton, which had to do with the indistinctness of
the image in refracting telescopes, which was
thought to arise from two sources, the different

refrangibility of different colors, and the shape of
the eyeglass. The latter was a matter of craft, the
former was thought to have no remedy; Newton
was cited as the authority for this despairing
conclusion on chromatic aberration, and though in
principle Newton had more than one opinion on
the subject, in practice he had given up on
refracting telescopes in favor of reflecting ones. 24
Kuler, who thought that Newton believed it was
impossible to perfect refracting telescopes, said
that Newton was wrong on this point, and to
correct him he wrote letters to the Philosophical
Transactions with his own prescription for making
refracting telescopes free of chromatic aberration.
The English optical instrument-maker John Holland
gave the rejoinder this time, deferring to Newton,
"that great man," who had proved the elimination
of aberration impossible. 25 Holland went on to
change his mind; the polemic with Kuler led him
to make experiments, the results of which differed
"very remarkably" from those in Newton's
Opticks.-'' By combining different kinds of glass,
Holland constructed achromatic lenses, which
greatly improved refracting telescopes, and for this
bold heterodoxy he was awarded the Copley
Medal in 1758. (The problem of indistinctness of
images in refracting telescopes was not completely
solved, and Cavendish would investigate it
thoroughly.) Thomas Melvil was more speculative
in his rejection of an explanation given by Newton.

'"Murdoch Mackenzie, " The State of the Tides in Orkney." I'T
46 (1749): 149-60. on 149.

'''Thomas Simpson. "Of the I'luents of Multinomials, and Series
Affected by Radical Signs. Which Do Not Benin to Converge Till
After the Second Term." W45 ( 1 748): 328-35, on 333.

2 "Jamcs Short, "An Account of a Book. Intitled, I'. I). Pauli Frisii
Mediolanensis, etc. Disquisitio mathematica . . . printed at Milan in
1752.. .." PT 48 (1753): 5-17. on 14-1.5.

-'Patrick Murdock. "A Letter . . . Concerning the Mean Motion
of the Moon's Apogee . . .." PT47 (1751 ): 62-74. on 62-63. 74.

--Alexis Claude Clairaut. "A Translation and Explanation of
Sonic Articles of the Book Intitled. Theorie de la Figure tie la Tern,"
TT4H < 1 753): 73-85, on 82-83.

-'"Extract of a Letter from Professor Kuler of Berlin, to the Rev
Mr. ( ;aspar Wetstein . . .." /'/'47 ( 1 751 ): 263-64.

24 D. T. Whiteside, ed., Tie Mathematical Tapers of Isaac S'evton
(Cambridge: Cambridge I niversity I'ress. 1969) 3: 442—13.

- 5 Lconhard Kuler. "Letters Concerning a Theorem of His, for
Correcting the Aberrations in the Object-Glasses of Refracting
Telescopes." PT 48 (1753): 287-96. John Dolland, "A Letter . . .
Concerning a Mistake in M. Killer's Theorem for Correcting the
Aberrations in the Object-Glasses of Refracting 'Telescopes." I'T AH
(1753): 289-91. on 289.

' John Dolland. "An Account of Some Experiments Concerning
the Different Refrangibility of Light." PTSO ( 1 758): 733-t3, on 736.

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Newton had attributed the different refrangibilities
of eolors to the different sizes or densities of the
particles of light of different eolors; Melvil said that
Newton had been misled by an "analogy" between
the refraction of light and the gravity of bodies, for
the true cause of different refrangibilities was the
different velocity of the ether pulses (not particles)
of different colors. This serious challenge to Newton
had observational consequences, and James Short
was ordered to make the observations and report
on them to the Royal Society; Melvil's hypothesis
did not stand up.-' 7 Henry Eeles's explanation of
the ascent of vapors was accompanied by an even
broader criticism of Newton. Eeles defended his
"hypothesis" of the fluid of fire against the dis-
approval of "our great modern philosopher" of the
use of hypotheses in general. Eels made the apt
observation that Newton himself used hypotheses
in his queries in the Opticks. Even gravitation, he
thought, would not have come to Newton without
an hypothesis. Since "supposition must always
precede the proof," if an hypothesis is rationally
founded, it should be tested; that is how science
advances.-' 8 (Cavendish implicitly agreed with
Eeles). Newton at mid century was still the
immortal Newton, but attitudes were conflicting
on his authority on this or that point. Newton's name-
was invoked to stand for correct practice in science,
but of course much of the research reported in the
Philosophical Transactions in the middle of the
eighteenth century proceeded without any specific-
connection with Newton's writings.

Scientific results had to be supported by
empirical ev idence, of course, but on the question
of whether greater trust was to be placed in theory
or in observation, the answer was not always
observation. The following discussion of the limits
of observational accuracy in relation to instruments
and theory is by the astronomical instrument-
maker and astronomer James Short, who at the
time was on the council of the Royal Society.
Short's purpose was to clarify the disagreements
over the observed shape of the earth and Newton's
gravitational theory of its flattening at the poles.
Critics of Newton's theory such as Clairaut had
made a mistake in regarding their observations as
absolutely exact (Clairaut denied that he placed
too much certainty in observations), while other
observers, such as Boscovich, had made a mistake
in thinking that the observations were too inexact

to draw any conclusions. When theory and
observation were compared, Short said, the theory-
could not be faulted until the disparity with
observation was greater than the errors attributed
to the instrument used and to its user, the observer.
Newton had a just appreciation of such limits,
Short said; Newton, for example, calculated the
ratio of the two diameters of the earth to be 229 to
230, that is, to three figures, not to four or more
figures, which would have been only a show of
precision. It would be "absurd" for an observer to
compute an angle to a second or a length to a part
of an inch if the instrument could only measure to
a degree or a foot. Mathematical results were
rigorously true, but observations always had
"certain limits." The error of the instrument was
itself one of the "data" Observers should follow
the "judicious caution" of Newton and read
Cotes's treatise on the subject of errors. Short
advised. 2 '' There was a high degree of sophis-
tication in the art of experiment and observation
in the middle of the eighteenth century, which
was thoroughly assimilated by Henry Cavendish,
who routinely assessed the limits of observation
and the consequent limits on theoretical cal-
culations of physical phenomena. Cavendish's
great reputation as an observer of precision de-
pended on his mastery of the theory and practice
of errors.

Errors implicit in instruments and in the
sense organs of observers could be diminished by
making repeated observations and taking their
mean. The mathematician Thomas Simpson
proved that it was better to take many observations
than a few and that by taking a mean of them, the
chances of small errors were reduced and the
chances of great ones were almost eliminated. This
method was used by astronomers, and Simpson
urged all others who made experiments to adopt
it. 30 Taking mean values was, again, standard
practice for Cavendish.

-T. Melvil, "A Letter . . . Concerning the Cause of the
Different Kcfran^ihility of the Rays of Light," />'/' 48(1753): 261-70.

-"Henry Keles. "Letters . . . Concerning the Cause of the Ascent
of Vapour and Exhalation, and 'Those of Winds: and of the Ccncral
Phaenomcna of the Weather and Barometer," /'7'49 (1755): 124-4"),
on 124-25.

"'Short, "An Account of a Book," 5-7.

'" Thomas Simpson. "A Letter . . . on the Advantage of "Taking
the Mean of a Number of Observations, in Practical Astronomy," PT
49(1755): H2-93.

l.U

Cavendish

In addition to multiplying his observations,
the observer was obligated to spell out their
circumstances. To establish a scientific fact, it was
not enough to report an experiment; unless others
were able to repeat it, it did not become the public
property of science.'' A variant of this requirement
of repeatability was the presence of multiple
observers and witnesses at the scene of a given
experiment. The Philosophical Transactions rarely
contained a joint paper, other than those by
committees, 32 but it was common for a paper to
record observations by several persons. Peter
Newcome of Hackney Academy reported that six
persons in his house felt an earthquake upstairs but
not downstairs. James Burrow said that the same
experience was reported by another person in an-
other house, though that report was not as valuable,
since it "depends indeed upon the perception of a
single person; whereas his /Newcome's/ is verified
by the sensations of six different ones." 33 Papers
often mentioned other persons, usually by name,
who were there and who looked through the
telescope or whatever. Testimonials were given, as
if in a court of law: in a witness, intelligence
counted, but so equally did profession, wealth, and
rank. 54 In a paper on a bright rainbow, Peter Davall
said that he heard about other bright rainbows from
"intelligent persons." 35 James Burrow heard about
an earthquake from "a very sensible Scotchman;" 36
he heard about another from a woman with
"superior" judgment, accuracy, veracity, and a
title." The president of the Royal Society was
assured that observers of an earthquake were not
"mean, ignorant, or fanciful" but truthful, "rational
and just." iK When a great storm struck a village, the
author of a report on it took two reliable men with
him to the spot to observe, the local physician and
clergyman. 3 '' The dimensions of an "extraordinary"
young man, two feet seven inches tall and twelve
or thirteen pounds, were confirmed by eight
witnesses, all "of figure and fortune" in the
neighborhood. 40 In the cases above, the importance
of the reliability of witnesses arose, in part, from
the uniqueness of the phenomenon, which unlike
an experiment could not be reproduced, though
the young man presumably could be measured
again. But the character of witnesses came up in
the accounts of experiments too: the French
electrical experimenter Jean Antoine Nollet had
used two servants who proved untrustworthy,

which, he said, "made me very delicate in the choice
of the persons who I was desirous should be admitted
to our experiments," and thereafter he was unwilling
to use "either children, servants, or people of the
lower class." 41 Henry Cavendish on occasion repeated
his experiments before or with other experimenters,
whom he selected from Fellows of the Royal Society,
whose reliability normally was beyond question.

Observers often gathered to make concerted
observations. For a repetition of J. H. Winkler's
experiments on passing odors through electrified
glass, one friend of Winkler and six Fellows of the
Royal Society met at William Watson's house. 42
Joint examinations of instruments were common. 43
So were observ ations of astronomical events involving
many observers working in coordination, including
observers abroad. 44 No one was more active in

"William Watson. "A Letter . . . Declaring That He as Well as
Many Others Have Not Been Mile to Make Odours Pass Thro' Glass
by Means of F.leetrieity " PT46 < 1 749): 348-56. on 348-49.

,2 The rare exception: John Bevis and James Short. "Astronomical
Observations Made in Surry-Street, London," PT 48 (1753): 301-5.

"Peter Newcome, "A Letter . . . Concerning the Same Shock
Being Felt at Hackney, near London," FT 46 (175(1): 653-54. James
Burrow. "A Letter . . . Concerning the Same Earthquake Being Felt
at Last Sheen, Near Richmond Park in Surrey." / J 7'46 ( 1 750): 655-56.

M As in the seventeenth century, a gentleman's word was seldom
questioned: Steven Shapin, " The 1 louse of Experiment in
Seventeenth-Century England," Isis 74 (1988): 373-404. on 398-99.

"Peter Davall, "A Description of an Extraordinary Rainbow
Observed July 15. 1748," PT 46 (1749): 193-95. on 195.

" James Burrow, "An Account of the Earthquake on Thursday
Morning. March 8, 1749. as Seen in the Inner Temple Garden, by
Robert Shaw (a Very Sensible Scotchman I Then at Work There." PT
46 (1749/50): 626-28, on 626.

■''Lady Cornwallis told James Burrow how she experienced an
earthquake: James Burrow, "Part of a Letter . . . Concerning an
Earthquake Felt Near Bury St. Edmund's in Suffolk . . .," PT 46
(1750): 702-5, on 703.

"William Barlow, "Concerning a Shock of an Earthquake F elt at
Plymouth, about One O'clock in the Morning. Between the 8th and
9th of Feb. 1 749-50," PT46 ( 1 750): 692-95, on 693.

''William Henry. "An Account of an Extraordinary Stream of
Wind. Which Shot Thro' Part of the Parishes of Tcrmonomungcn
and Urney, in the County of Tyrone, on Wednesday October 11.
1752," PT 48(1753): 1-4, on 1.

4 "John Brow ning. "Extract of a Letter . . . Concerning a Dw arf."
/T47(1751): 278-81. on 279.

■"Abbe Nollet, "Extract of a Letter . . . Accompanying an
Examination of Certain Phaenomena in Electricity . . .," PT 46
(1749): 368-97, on 377.

'-'William Watson, "An Account of Professor Winkler's
Experiments Relating to Odours Passing through Electrified Globes
and Tubes . . .." /7'47 (1751): 231-41. on 237-38.

4l John Smeaton. "An Account of Some Experiments upon a
Machine for Measuring the Way of a Ship at Sea," PT 48 (1754):
532-46, on 555, 537. 559-40.

■"The subject here is the parallax of Mars, determined by
observations at two places on earth, in France and in l^ngland. "A
Letter from Monsieur de L'lsle, of the Royal Academy of Sciences at
Paris, to the Reverend James Bradley . . .." PT48 (1754): 512-20.

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cooperative scientific ventures in the middle of the
eighteenth century than James Short. At his own
house, Short with three others observed the
occultation of Venus by the moon. 45 At Birch's
house, he and two others observed the transit of
Mercury, and at five other locations observations of
this event were made by others. 4 '' To observe an
eclipse of the sun, an excursion was made to
Morton's castle north of Fldinburgh by Short,
Morton, and Pierre Charles Le Monnier who had
come from Paris for the purpose. This excursion
was only one part of a wider effort in Scotland to
observe the eclipse, coordinated by cannon fired
from Edinburgh Castle. Bad weather obscured this
eclipse in Edinburgh, but observations were made
at Morton's and at nine other locations in Scotland
(with poor agreement owing, Short believed, to
some observers' want of "sufficient practice"). 47
Henry Cavendish often engaged in experimenting
with others, sometimes in private but more often in
committees of the Royal Society.

The occasional meteor or earthquake was
experienced by the unaided sight or touch of the
observer, who had no choice in the matter, but by
the middle of the eighteenth century most
scientific observations were made with the aid of
instruments. The Philosophical Transactions at this
time contained many papers describing new
instruments, usually written by their makers,
giving full details of their construction and use
together with drawings. In his account of a new
pyrometer, John Smeaton said that its construction
and use were clearer from the drawing than "from
many words." 48 What Smeaton said of his
pyrometer was true in general: the elaborate,
detailed, and scaled drawings, with charioscuro,
were as integral to papers on instruments as
drawings of specimens were to botanical papers.
Apart from the occasional surgical instrument, 44 the
instruments described in the journal were designed
to aid in the production and observation of
phenomena (e.g., air pumps) 50 or, as in most cases,
to measure (e.g., micrometers, thermometers, and
clocks). Users of instruments explained their
principles and their use in experiments and, as a
rule, sang their praises. In the case of Smeaton's
pyrometer, for example, which was used to
measure the expansion of metals, the point of
contact of the piece of metal with the point of the
micrometer screw was determined not by sight or

135

touch but by hearing, the more discriminating
sense. This pyrometer was capable of measuring an
expansion to an accuracy of one four thousandth
part of an inch, and repeated measurements with it
differed by no more than one twenty-thousandth
part of an inch. Its sensibility, Smeaton said,
"exceeds any thing I have met with." 51

The need for instruments was obvious —
almost: from Norwich, a keeper of records of the
weather complained that many people in his
neighborhood judged the weather only by their
"outward senses," without resorting to the
thermometer, and accordingly they made mistakes
such as putting the hottest day in June when it was
in July. 5 - In astronomy, the importance of exact
instruments had long since been demonstrated,
though the point was still thought worth making in
the middle of the eighteenth century. James
Bradley, for example, spelled out the ease for
instruments as the means of discovery: not long
ago, he said, astronomy had seemed perfected and
no further progress was expected, a conclusion
based on the instruments at hand, the telescope
and the pendulum clock, and on the theory of "our
great Newton." But Bradley's own discoveries
proved that this confidence was misplaced. He had
first discovered the aberration of light, and now he
had discovered another annual change in the place
of the stars, perceptible only because, he said, "of
the exactness of my instrument." Like his first, his
second discovery was the result of his lifelong
search — this guided by theory — for an annual

♦'The other observers at Short's were John Bevis, John Priflgle,
and the duke of Queensbury. John Canton observed it at his house
too. John Bevis. "An Occultation of the Planet Venus by the Moon in
the Day 'lime Observed in Surrey-Street." /'/' (1751): 159-63.
Bradley also observed it, as written tip by James Short, ". . . Bradley's
Observation of the Occultation of Venus bv the Moon," PT 47
(1751): 201-2.

^The other observers were Sisson. Bird, Smeaton. Canton, and
Macclesfield.

47 Jamcs Short, "An Eclipse of the Sun, Julv 14 1748. . .," PT4S
(174S): 582-97.

■•"John Smeaton, "Description of a New Pyrometer, with a Tabic
of Experiments Made Therewith," / r /'48 ( 1 754): 598-61 i, on 60(1, 60S.

♦The surgical instruments were knives, forceps, and puncturing
instruments; e.g., translation of M. le Cat, "A New Trocart for the
Puncture in the Hydrocephalus, and for Other Evacuations, W hich
Are Ncccssarv To Be Made at Different Times," PT 47 (1751):
267-72.

■"•John Smeaton. "A Letter . . . Concerning Some Improvements
Made by Himself in the Air-Pump," PT47 (1752): 415-28.

sl Smcaton, "Description of a New Pyrometer," 600.

"William Anderson, "Extract of a Letter . . . Concerning the
Hot Weather in July Last," PT 46(1750): 573-75, on 574.

Cavendish

parallax of stars arising from the earth s orbital motion.
Bradley had made his discovers' of the aberration of
light at the time Lord Charles Cavendish entered the
Royal Society; he made his discovery of the
nutation of the earth's axis caused by the pull of the
moon on the earth's equator while I Ienry Cavendish
was at the university. The cause of nutation was
understood theoretically, but the nutation Bradley
discovered had not been foreseen. I Iere was an
object lesson in science: theory did not predict
everything but was indebted to observations and
experiments, which pointed to the "great advantage
of cultivating this, as well as every other branch of
natural knowledge, by a regular series of observations
and experiments." The "more exact the instruments
are . . . and the more regular the series of observations
is . . . the sooner we arc enabled to discover the cause
of any new phaenomenon." Bradley advised
astronomers to begin by examining the correctness of
their instruments, an injunction Henry Cavendish
would carry out in every branch of physical science. 5 " 1
It was not, of course, just in astronomy that
quantitative work was done. It might appear
anywhere: draughts given to, and the blood taken
from, a patient; 5 - 4 bills of mortality;" the path of
lightning; 5 '' the heat of a cave. 57 Henry Miles, a
clergyman with a wide-ranging interest in quantities —
he reported the "bigness" of a fungus, 210th part of
an inch 58 — published an unusual paper for the
Philosophical Transactions, a philosophical essay. The
topic was quantity: prompted by a treatise by
Thomas Reid, in which ratios were applied to
virtue, Miles set out to determine what things were
properly subject to mathematical proof, and thus
beyond dispute. Miles, who believed that
affections and appetites could not be reduced to
quantity, identified quantity with "measures,"
which required a "standard," so that "all men,
when they talked of it, should mean the same
thing." 5 '' In the Philosophical Transactions, we see
evidences of agreement on the importance of
measures and standards. The physician and sophisti-
cated experimentalist John Pringle, who would
become president of the Royal Society, laid down
"standards" in his quantitative ranking of salts by
their power to resist putrefaction. 6 " The introduc-
tion of standards in science was Henry Cavendish's
goal as a quantitative experimentalist.

The balance and the thermometer acquired
a new importance in science because of their use in

quantitative chemistry; by contrast, in the model
quantitative science, astronomy, the thermometer
played a very subordinate role and the balance
none at all (until Cavendish, at the end of his life,
weighed the world with a kind of balance).
Pneumatic chemistry, as Cavendish would soon
show, made use of specific gravities to distinguish
different species of air; as if to point the way, the
physician Richard Davies published a history of
tables of specific gravities, with their "manifold
applications ... in Natural Philosophy," including
the recent work of his contemporaries Ceorge
Graham, James Dodson, and John Kllicott with his
"exquisite assay-scales," and to his own work with
his sensitive hydrostatical balance built by Francis
Hauksbee.'' 1 Cromwell Mortimer, secretary of the
Royal Society and a physician who studied the
effects of chemical remedies in diseases, set out
the uses of the thermometer in chemistry.
Chemistry, the "most extensive Branch of Experi-
mental Philosophy," suffered from the unrepeatability
of its experiments. The reason, Mortimer said, was
the failure to record the heat: the chemist's laboratory
should be equipped with "various Sorts of Thermo-
meters, proportion'd to the Degree of Heat he in-
tends to make use of," and the chemist should keep
track of the time the heat is applied, observing "his
Clock with as much Exactness as the Astronomer."''-
Cavendish's most important experimental work

sl James Bradley. "A Letter . . . Concerning an Apparent Motion
Observed in Some of the Fixed Stars," PT45 (1748): 1-43. on 2-4.

^George Bayly, "A Letter . . . of the I'se of the Hark in the
Small-Pox," PT 47 (1751): 27-31.

"James Dodson, "A Letter . . . Concerning an Improvement of
the Hills of Mortality," /T 47 (1752): .533-40.

^William Henry, "Account of an Extraordinary Stream of Wind
in the Parishes of Thermonomungan and Urney, in the County of
Tyronc"/T48(1753): 1-4.

"William Arderon. "An Account of Large Subteranneous
Caverns in the Chalk I lills Near Norwich," /'7'45 ( 1 748): 244-47.

''"Henry Miles, "A Letter . . . Concerning the Green Mould on
l ire-Wood: With Some Observations of Mr. Baker's upon the
Minuteness of the Seeds of Some Plants." PT46 ( 1 749/50): 334-38.

v '\ Ienry Miles. "An Essay on Quantity; Occasioned by Reading a
Treatise, in Which Simple and Compound Ratios Are Applied to
Virtue and Merit, by the Rev Mr. Reid." /'7'45 < 1748): 505-20, on 506.

'■"John Pringle. "A Continuation of the Experiments on Sub-
stances Resisting Putrefaction," PT46 ( 1 7.50): 525-34.

'■'Richatd Davies, "Tables of Specific Gravities, Extracted from
Various Authors, with Some Observations upon the Same," PT 45
(1748): 416-89.

''-Cromwell Mortimer, "A Discourse Concerning the Usefulness
of Thermometers in Chemical Experiments; and Concerning the
Principles on Which the Thermometers Now in I se Have Been
( instructed; Together with the I )escription and I ses of a Metalline
Thermometer. Newly Invented." PT 44 (1746/47): 672-95. on 673.
'This paper was first read in 1755 and printed later with revisions.

Science

was done in chemistry; in which he used the
balance as an astronomer did his clock and
micrometer, and in heat, in which his principal
instrument was the thermometer.

Electricity was the liveliest experimental
science at the time Cavendish was at the
university. Stephen Hales observed on a visit to
London, where he saw electrical experiments
performed, that in this "new field of researches
there are daily new discoveries made." 63 As we
have seen, Cavendish's father was active in this
field, a collaborator of Watson. It was Watson who
introduced the Royal Society to the device that
transformed the experimental field and guided
Franklin to his understanding of electricity, the
Leyden jar/* 4 It was Watson too who gave the
Society an account of Franklins book on electricity,
consisting of four letters to his Fnglish cor-
respondent, Peter Collinson, all or parts of which
had been read at the Royal Society. This book,
Watson said, shows Franklin to have "a head to
conceive, and a hand to carry into execution."
Nobody, Watson said with characteristic candor and
generosity, knows electricity better than Franklin. 65
There was a sense among investigators that they
were no longer working on the periphery of the
subject but on the "nature" of electricity and, as
John Ellicott put it, on the "general principles" and
the "laws of electricity." 66 Investigators were
talking about "quantities" of electricity. Twenty
years later Henry Cavendish would base his
quantitative experimental and mathematical
researches on the principles of electricity drawing
on Watson's and Franklin's work.

•The contents of the Philosophical Transactions
reflected the great interest taken in electrical effects
in the laboratory of nature. After Franklin had
proposed experiments on lightning, Watson together
with several Fellows of the Royal Society tried to
draw electricity during a thunder storm; they
failed, but others in London, such as John Canton
and John Bevis, succeeded. 67 Daring experiments
on lightning were reported from Philadelphia,
Paris, and elsewhere around the world.

Lightning was a new phenomenon insofar
as it was explained by an electrical hypothesis.
Otherwise it belonged to the general category of
violent events that were a staple of the Philosophical
Transactions (as they were of life in the eighteenth
century). Provided they were sufficiently devas-

tating, incidents of thunder and lightning with
their attendant "melancholy accidents" were
reported in the journal independently of electrical
science. 68 Lightning struck a ship in a "violent
manner, disabling most of the crew in eye and
limb." 69 The mainmast of another ship was
shattered when a "large ball of blue fire" rolled
over the water and exploded "as if hundreds of
cannon had been fired at one time." 711 In a valley, in
the "violence of the storm," a cloudburst and flash
flood threw up "monstrous stones," which were
"larger than a team often horses could move." 71 A
meteor that looked like a "black smoky cloud"
split an oak, and its "whirling, breaks, roar, and
smoke, frightened both man and beast." 72 Clouds
and auroras were seen to turn "blood-red. " 7; ' Plagues
of locusts "hid the sun," and undeterred by "balls
& shot," they "miserably wasted" the land. 74
Victims of the "black vomit" experienced delirium
"so violent" that they had to be tied down so that
they did "not tear themselves in pieces." 75 Bitten

"Stephen Hales. "Kxtract of a Letter . . . Concerning Some
Eleetrieal Experiments," PI 45 (1748): 409-410. on 410.

M William Watson, "A Sequel to the Experiments and
Observations Tending to Illustrate the Nature and Properties of
Electricity," PT 44 (1747): 704-49, on 709 ff.

"William Watson, "An Aetount of Mr Benjamin franklin's
Treatise, Lately Published. Intituled, Experiments and Observations
on Electricity, Made at Philadelphia in America." PR 47 (1751):
202-11, on 210.

"'John Ellicott, "Several Essays Towards Discovering the Laws
of Electricity . . .." PT 45 (1748): 195-224.

'■'William Watson, "A Letter . . . Concerning the Electrical Experi-
ments in England upon Thunder-Clouds,"/ J 7'47 (1752): 567-70. John
Canton, "Electrical Experiments, w ith an Attempt to Account for Their
Several Phaenomena; Together with Some Observations on Thunder-
Clouds," PI -iH (1755): 350-58. There were many more papers at this
time on lightning experiments.

""William Borlase, "An Account of a Storm of Thunder and
Lightning in Cornwall," PT4S (1753): 86-93.

'■'John Waddell, "A Letter . . . Concerning the Effects of
Lightning in Destroying the Polaritv of a Mariner's Compass," PT
(1749): 111-12.

'"Mr. Chalmers. "An Account of an Extraordinary fireball
Bursting at Sea." / J 7'46(1749): 366-67. on 366.

71 "An Account of a Surprising Inundation in the Valley of St
John's Near Kesw ick in Cumberland, on t he 22d Day of August 1749,
in a Letter from a Young Clergyman ... ," /'7'46 (1749/50): 362-66.

72 Thomas Barker, "An Account of an Extraordinary Meteor
Seen in the County of Rutland, which Resembled a Water-Spout."
/ J 7'46(1749): 248-19.

'Hcnrv Miles, "A Letter . . . Concerning an Aurora
Borcalis . . .." PT 46 (1749/50): 346-18, on 548. William Stukeley,
"'The Philosophy of Earthquakes." /'7'46 ( 1 750): 731-50. on 743.

H "An Account of the Locusts, w hich Did Vast Damage in Walachia.
Moldavia, and Transilvania, in the Years 1747 and 1748 . . . by a Gentle-
man Who Lives in Transilvania." PI 46 (1749): 30 -37, on 30 H.

""Extract of So Much of Don Antonio De Llloa's f.R.S.
Account of His Voyage to South America, as Relates to the

I Mi

Cavendish

by a mad dog, a horse in its agony gave off breath
"like smoke from a chimney-top." 7 ' 1 Children were
carried away by contagion — a five-year-old girl was
observed as she coughed up a "large quantity of
white rotten flesh." 77 Fright and misery would end
only because the world was going to end, by
astronomical calculation, when it spiraled toward
the sun and would "necessarily be burnt." 7K In the
laboratory the v iolence of nature was simulated,
and if in the laboratory it was moderated, it was
violence all the same, and dangerous; lacking
apparatus with effective safety features,
investigators sometimes had been "intimidated"
and "deterred." 7 '' The Leyden jar manufactured a
form of lightning and was itself the inspiration for
the electrical understanding of lightning and, as
well, of thunder. 80 The "violent explosion of glass
drops" in the laboratory was likened to volcanoes. 81

The Philosophical Transactions was, among
other things, a sometimes lurid newspaper for the
learned. Reading the journal was not a quieting ex-
perience. "Letters" from a participant or observer
or victim at the scene would begin "I was much
surprised," then go on to relate grisly details. Most
of the medical papers described extreme pathologies
and monstrous productions in more or less ordinary
language, which did not spare the reader. The most
frightening event of all was an earthquake.

The year 1750, one Fellow of the Royal
Society observed at the time, "may rather be called
the year of earthquakes, than of jubilee." These
earthquakes occurred as if on command of the
Royal Society: their center was thought to be
London, "the place to which the finger of God was
pointed."*- Henry Cavendish was in his second
year at the university when an entire issue of the
Philosophical Transactions was given over to the
subject. Presented as an appendix to the regular
issues, it consisted of fifty-seven papers submitted
to the Royal Society dealing with several,
principally four, earthquakes in Fngland and the
Continent in 1750. The earthquakes that year were
only a curtain raiser. The great earthquake of 1755
destroyed Lisbon and, what is important to us,
prompted John Michell to explain earthquakes
scientifically.

Half of the observers reporting on earth-
quakes in the Philosophical Transactions were
Fellows of the Royal Society. Fellows also collected
testimony and communicated letters from others

for publication in the journal. Fellows or otherwise,
reporters of the earthquakes rarely observed the
direction, time, and duration of the shock. 83 In this
connection, it is noteworthy that none of the
observations was made by an astronomer. As
earthquakes go, those of 1750 were not severe —
buildings did not come down, persons were not
hurt — but witnesses nonetheless described them
as "violent." People thought first of gunpowder,
cannon, the explosion of a magazine or powder mill
or a mine, or lightning. 84 At Martin Folkes's house,
Folkes, Macclesfield, and two other visitors were
"strongly lifted up, and presently set down again,"
while the coachmen standing outside Folkes's door
feared that the house would come down on them. 85
Gowin Knight's house "shook violently," and the
duke of Newcastle's servant came to Knight to tell
him what had happened at his house, and a man
from Greenwich told him that all the way from
London Bridge the people were frightened. 86
Animals were frightened too: a cat was startled, a
dog was terrified, cows and sheep were alarmed,

Distemper Called There Vomiio Pricto. or Blaek Vomit,"/'/' 46
(1749-50): 134-39, on 135.

"'John Huxham, "A Letter . . . Containing an Account of an
I lorse Bit by a Mad Dog," P T Mi ( 1 750): 474-78, on 478.

"John Starr. "An Aeeotint of the Morbus Strangulatorius," PT Mi
(1750): 455-46. on 459.

'"Leonard Kuler. "Part of a Letter . . . Concerning the Gradual
Approac h of the Earth to the Sun." PT Mi (1749): 205-5, on 204.

Tor this quotation, we no outside the time when Cavendish
was at the university to the time when he began his electrical
experiments at home: C. L. Kpinasse. "Description of an Improved
Apparatus for Performing Electrical Experiments, in Which the
Electrical Power Is Increased, the Operator Intirely Secured from
Receiving Any Accidental Shocks, and the Whole Rendered More
Convenient for Experiments than Heretofore," PT 57 (1767):
186-91, on 1X8.

""I lenry Keles, "A Letter . . . ( Concerning the Cause of Thunder,"
PT 47 (1752): 524-29. Keles took exception to the standard analogy
between fired gunpowder and thunder; he had an up-to-date
explanation based on the fire observed in electrical experiments.

"'Claude Nicolas Le Cat, "A Memoir on the Laerymae
Batavicae, or Glass-Drops, the Tempering of Steel, and
Effervescence, Accounted for by the Same Principle," PT 46 (1749):
1 75-88, on 1 87.

"-William Stukelev, '*. . . Concerning the Causes of
Earthquakes," PT 46 (1750): 657-69, on 669; "The Philosophy of
Earthquakes," / J 7'46 (1750): 751-50. on 752.

"'As was noted by W. Cow per. Dean of Durham, ". . . Of the
Earthquake on March 18, and of the Luminous Arch. February 16,
1749," / J 7'46 (1750): 647-19, on 648.

"^Smart Lcthieullier, ". . . Of the Burning of the Steeple of
Danbury in Essex, by Lightning, and of the Earthquake," PT Ah
(1749/50): 61 1-13.

"'Abraham Trembly, "Extract of a Letter, Concerning the
Same," PTM> (1749/50): 610-1 1, on 61 1.

•""Gowin Knight, "An Account of the Shock of an Earthquake
Kelt Feb. 8 1749-50." PT 46 ( 1 749/50): 605-4, on 605.

Science

130

fish were disturbed, a horse refused water, crows
took flight. 87 Sensations were described variously,
as "falling into a fit. xx "Roger Pickering, a clergy-
man who was a close observer of the weather and
natural curiosities, gave a detailed account of his
sensations while lying in bed when the quake
occurred; he also gave his reflections, which led him
beyond the "secondary causes" of the quake to the
grandeur and majesty of the "Lord of Nature." 89

Just what these "secondary causes" were was
the scientific question of the day, to which various
answers were given, two of which were published
together with the collected reports of the earth-
quake in the Philosophical Transactions. Stephen
Hales, a clergyman, said that both the ordinary and
the extraordinary events of nature were caused by
God, but that they did not lie outside natural
explanation for that reason. Hales first described
his sensations while lying in bed during a tremor;
then he explained them by referring to experi-
ments from his Statical Essays: an earthquake is
caused by the explosive lightning of a sulphurous
cloud, which ignites the rising sulphurous vapors in
the earth. 90 A further explanation of earthquakes
was given by another clergyman, William Stukeley.
After a perfunctory consideration of the religious
view, Stuckley turned to the subject of interest in
the Philosophical Transactions, the physical causes;
rejecting subterranean vapors, he attributed earth-
quakes to "electrical shock, exactly of the same
nature as those, now become very familiar, in
electrical experiments." With reference to Franklin,
Stukeley said that the "little snap, which we hear in
our electrical experiments," is the same snap, only
magnified, that we hear in thunderstorms. When a
cloud rises from the sea and discharges its contents
on the earth, an earthquake results. Having gotten
to know the "stupendous powers" of electricity by
experiment, he turned to electricity to explain the
"prodigious appearance of an earthquake." 91
Stukeley's and Hales's causes of earthquakes,
electricity and vapors (or gases), were the two main
experimental subjects in Britain in the second half
of the eighteenth century, and they were two of
Henry Cavendish's great experimental fields (heat
was a third).

The catastrophic Lisbon earthquake in
1755 filled the last roughly hundred pages of the
volume of the Philosophical Transactions for that
year and much of the next year's. 92 Unlike the

accounts of the earlier earthquakes of 1750, these
dwelled on loss of life and physical destruction.
This earthquake would not be the last scourge of
humanity to prove a stimulus to science. The most
important response was John Michell's paper on
the cause of the earthquake "So Fatal to the City
of Lisbon" and on earthquakes in general, printed in
the Philosophical Transactions for 1760. 93 We will move
ahead in time to consider this paper, since it, more
than any other work, set the standard just as Henry
Cavendish joined the scientific circles of London.

Michel! and Cavendish's acquaintanceship,
if not their friendship, began no later than the year
of Michell's paper on earthquakes in 1760. That
year, at Cavendish's first dinner as a member of the
Royal Society Club, Michell was present as a guest,
and in later years Cavendish often brought Michell
as his own guest. 94 In 1760, Michell and Cavendish
were both elected Fellows of the Royal Society,
and in that same year and before their elections,
Michell's paper on the causes of earthquakes was
read in five consecutive meetings of the Society.
Cavendish was present at all of these meetings,
three times as a guest of his father. 95 Michell's
subject, the earth's interior, linked his and
Cavendish's interests thereafter.

For most of his life Michell was a
clergyman, but in his paper on earthquakes he
made no reference to providence or any other
religious idea. He disagreed with both Hales and

»W46 (1750): 618, 621, 651, 682, and passim.
"Thomas Birch, "An Account of the Same." PT 46 (1749/50):
615-16, on 616.

"''Roger Pickering, ". . . Concerning the Same," /'7'46 ( 1 749/50):
622-25, on 625.

'"'Stephen Hales, "Some Considerations on the Causes of
Earthquakes," /7'46 (1750): 669-81.

"William Stukeley, ". . . On the Clauses of Earthquakes";
"Concerning the Causes of Earthquakes"; and " The Philosophy of
Earthquakes," PT 46 (1750): 641^*6, on 642^; 657-69, on 663;
731-50.

''-'About the last hundred pages of volume 49. part I. 1755, and
much of part 2, 1756.

"John Michell, "Conjectures Concerning the Clause, and
Observations upon the Phacnomcna of Earthquakes; Particularly of
that Great Earthquake of the First of November. 1755, w hich Proved
So Fatal to the City of Lisbon, and Whose Effects Were Felt as Far
as Africa, and More or Less Throughout Almost All F^urope," PT 5\
(1760): 566-634.

♦•Entry for 14 Aug. 1760, Minute Book of the Royal Society
Club, Royal Society, no. 4. In 1766 the minutes began to identify
visitors with the members who invited them; in that way we learn
that Cavendish repeatedly invited Michell when Michell was in
town on visits.

«The meetings were on 28 Feb., 6, 13, 20, and 27 Mar. 1760.
Royal Society, JB, 23: 782, 795, 800, 802, and 807.

Cavendish

Stukclcy, w ho located the cause of earthquakes
above the earth. Volcanoes were proof that fires
could exist underground, without contact with the
air, and by analogy Michell reasoned that volcanoes
and earthquakes had the same cause. Pent-up
water vapor falling into underground fires was the
cause of earthquakes. The elastic force of heated
vapor exceeded even gunpowder in producing
"sudden and violent effects." 1 "' Conceiving of the
earth not as "heaps of matter casually thrown
together" but as "uniform strata," Michell developed
a mechanical theory of the propagation of waves
through the elastic substance of the earth. By the
same principles that explained the motions of the
heavenly bodies, the motions of the earth were
explained: earthquakes were a dynamic phenome-
non, explicable by the laws of motion. The elastic,
stratified earth was set in motion by the expansive
force of heat. What Michell proposed was more
than a theory of earthquakes; it was an exact
science of the earth.

When we look at the empirical support that
Michell brought to his theory, we recognize in it a
vindication of the motivating ideals of the Royal
Society. The natural histories that Bacon expected
from Salomons House had been tried many times
by the Royal Society, often without much benefit,
but the natural histories of earthquakes led to
science. Michell was able to derive the cause of
earthquakes, he said, because of the bounty of facts
of the earthquake of 1755, the worlds best
documented earthquake. Many of the facts were
collected in volume 49 of the Philosophical
Transactions and in a separate publication on the
history and science of earthquakes. Michell's paper
of 1 760 is replete with references to the
Philosophical Transactions, most from volume 49 but
some earlier. Michell's use of histories was
sophisticated; he acknowledged that observations
were often carelessly made and reported, but the
"concurrent testimonies" of so many persons
established the main point. He selected accounts
having the "greatest appearance of accuracy" and
took a "mean" of them in computing the time,
location, and depth of the Lisbon earthquake.'' 7

Michell's paper has another connection with
the Society's founding ideals through its references
to the experiences of artisans, such as their
disastrous experience in casting a cannon in a damp
mold, resulting in an explosion of the "greatest

violence." 9 * The explosion of coal damp in mines
was powerful but not enough for earthquakes,
Michell said. For that, water had to be converted
into steam, and the steam engine was Michell's
example, taken from the world of artisans.

Like earthquakes, the weather was regarded
as a great force of nature. w The atmosphere was a
source of the most violent events, as Hales and
Stukeley had argued in their theories of
earthquakes. Its normal behavior was the occasion
of endless reports to the Royal Society. The
barometer reading, the rainfall, the temperature,
usually including the mean and the highest and the
lowest, were reported from far and near, Madeira,
Dublin, Charles- Town, and Tooting. Jurins method
of recording temperature was still practiced, but
standardization was a remote ideal. Temperatures
could be given in Fahrenheit, Reaumur, and in
relationship to the heat of human blood. 100 The
clergyman Henry Miles wrote about the
thermometer, an instrument which Newton had
considered and which several others had tried to
bring to "greater Perfection." This much agreement
was now widespread, Miles said: thermometers
made with mercury work the best. The credibility
of the mercury thermometer was implicitly put to
the test in the extreme climate of Siberia, in which
Johann Georg Gmelin recorded temperatures as
low as minus 120 degrees Fahrenheit, which he said
was scarcely believable "had not experiments, made
with the greatest exactness, demonstrated the reality
of it." 101 William Watson used nearly the same words:
Gmelin's observations, however "extraordinary,"
were "scarce to be doubted," since they were made
with "all possible exactness" and agreed with
readings made by others under his direction in
different parts of Siberia." 1 -' Beginning with this
remarkable weather report, Henry Cavendish
would make a study of the contraction of mercury
on freezing, thereby clarifying the behavior of

'"■Michell. "Conjectures," 594.
"Ibid, 629.
''"Ibid, 595.

"Henry Miles, " . . . On (he Same." PT46 (1749): 607-9.

""'The weather at the time of earthquakes was recorded; eg.,
William Arderon, "Extract of a Letter . . . Concerning the I lot
Weather in July Last." / J /' 46 < 1750): 573-75.

""John I-'othergill's extracts from Gmelin. "An Account of Some
Observations and Experiments Made in Siberia . . .." PT4S (1748):
248-62, on 260.

'"'W illiam Watson. "A Comparison of Different Thcrmometrical
Observations in Siberia." /'7'48 ( 1 753): 108-9.

Copyrighted malarial

Science

141

thermometers made with mercury. The naturalist
William Arderon, who published frequently on the
weather in Norwich, kept a record of the constant
temperature in a cavern under nearby hills, which
he compared with the mean of the hottest and
coldest temperatures above ground, finding them
almost identical, and noting that the temperature
of the Norwich cavern was within a degree of that
of the cave beneath the Paris Observatory. 1(U This
measure of the average climate Henry Cavendish
would expand on a worldwide basis. George Graham
noted that the magnetic variation at London was
not regularly published, 104 and although Cavendish
kept a regular record of it, he did not publish it
either. Auroras were a regular feature of the journal, 105
and Cavendish would publish his observations of
an aurora.

Some of the same persons who worked in
natural philosophy worked at the same time in
natural history. To William Watson the study of
living nature had the same goal as the study of the
physical world: "general laws" of nature. 106 A
strong advocate of Linnaeus, Watson published on
the sex of plants, the discovery of which, he
thought, was as important as that of the circulation
of the blood in animals. The Royal Society
Croonian Lectures in 1747 were given by the
physician Browne Langrish, who explained muscu-
lar motion by Newton's attracting and repelling
forces, giving credit, and dedicating his lectures, to
Stephen Hales for showing that particles of air are
attracted to solids. 107 The physician Charles Morton
published a paper on the same subject, muscular
motion, which he, a professed "Newtonian," laid
out in observations and experiments, lemmas, and
scholia. As was traditional, Morton regarded his
subject as belonging to "natural philosophy." 108
Nevertheless, in practice, for some men of science,
there was a sharp difference: Cavendish did re-
search in all parts of natural philosophy, as he
accepted it, which was as physical science; he did
no research on plants and animals to understand
their laws.

The Royal Society continued to honor
Bacon's ideal of a scientific society that worked to
"relieve the necessities of human life." At the time
Cavendish was studying at the university, the
Philosophical Transactions contained a large number
of papers that were at least partly directed to
utilitarian interests; these dealt with mechanical

power, manufactures, gunnery, navigation, medicine
and health, and the prevention of disasters. John
Smeaton showed the Royal Society a tackle of
twenty pulleys small enough to fit into the pocket.
With another block of twenty pulleys, he offered
an Archimedean-like demonstration of one man
lifting a gun and carriage aboard a naval ship. 109
William Brownrigg offered lemmas and propositions
on salt-making, which William Watson hoped
would do what the Royal Society's histories of salt-
making had not, overcome Britain's disadvantage
in this trade. 110 John Mitchell gave a Baconian
history of potash-making, which in England, he
said, was "practised only by the vulgar, and
neglected and overlooked by the learned." 111 In
Newgate prison, infectious fevers killed convicts
and, worse, officers of courts of justice who were
exposed to convicts during trials. 112 On Stephen
Hales and Lord Halifax's recommendation. Captain
Henry Ellis installed Hales's ventilators in his ship,
which caused candles to burn better and bells to ring
louder and slaves and other cargo to hold up better. 1 15
Electrical healing was more often the product of
enthusiasm than of repeatablc experiments, and
claims for it were received with caution; but that
electricity had some medical advantages seemed
evident to everyone at the time. 114 Bills of

""Arderon also measured the temperature of a spring in the
cavern, a method Cavendish would recommend as well. William
Arderon. "An Account . . .," 247.

,M Gcorgc Graham. "Some Observ ations. Made Dunns; the Last
Three Years, of the Quantity of the Magnetic Variation . .." PT 45
(1748): 279-80, on 280.

l0S John Martyn, "A Letter . . . Concerning an Aurora Borealis
Seen February 16.' 1 749-50," PT 4k ( 1 749/50): 545.

'"'William Watson, "Some Observations upon the Sex of
Flowers," PT 47 (1751): 169-83 on 179, 182-85.

'"'Browne Langrish, "Three Lectures on Muscular Motion."
supplement to the / J 7'44 ( 1 747).

""Charles Morton, "Observations and Experiments upon Animal
Bodies. Digested in a Philosophical Analysis, or Inquiry into the Cause
of Voluntary Muscular Motion," PT47 (1751 ): 305-14, on 308. 314.

""John Smeaton, "A Description of a New Tackle, or
Combination of Pulleys," PT 47 (1752): 494-97.

""William Watson's abstract and review: "An Account of a
Treatise by Wm Brownrigg. . .." /'7'45 ( 1 748): 351-72.

"'John Mitchell, "An Account of the Preparation and Uses of
the Various Kinds of Pot-ash," PT45 (1748): 541-63, on 541.

"^Stephen Hales and John Pringle were consulted on how to
achieve purity of air at Newgate, and it was decided that Hales
should design a ventilator lor the purpose. John Pringle. "An
Account of the Gaol-Fever with Which Sev eral Persons Were Seized
in Newgate," PT 48 (1753): 42-54.

"'Henry Ellis, "A Letter to the Rev Dr. Hales . . .," PT 47

(1751) : 211-16.

ll4 William Watson, "An Account of Dr. Bianehini's Recueil
d 'experiences faites a Venise sur le medicine eJectrique," PT 47

(1752) : 399-406.

142

Cavendish

mortality documented the relative unhealthiness of
various places, useful knowledge for calculating
annuities on lives. Medical waters were analyzed
for their contents. Improvements were made in
nav igation, such as in the mariner's compass, the
invention of which, the improver Gowin Knight
said, had "probably been of more general and
important use to human society, than the invention
of any one instrument whatsoever." 11=1 To celebrate
the recent peace, six thousand rockets were fired
without incident in Green Park, following Stephen
Hales's recommendation for preventing fire by
spreading a layer of dirt or fine gravel over the wood
floor. 1 "' The Philosophical Transactions had countless
papers on lightning rods, a direct application of
science; this application Henry Cavendish became
involved with through his work in the Royal Society'.

A reflection of eighteenth-century education,
frequently astronomy and classics were combined
in the Philosophical Transactions. William Stukeley
referred to Thales's account of a solar eclipse to
remind historians that they could profit from
astronomy." 7 There was a tradition of astronomical
reasoning in history; just as in science, in chronology
Newton now received gentle criticism.' w The
contemporary university education in mathematics
and classics resulted in exacting studies of

antiquity." 1 ' From China a Jesuit who had worked
out a chronology of ancient China proposed to do the
same for Chinese astronomy. 1 -'" Henry Cavendish
contributed even to this field, as we will see, with
his study of the Hindoo calendar.

Nearly all of the scientific problems Henry
Cavendish worked on during his long career were
problems that were addressed in the Philosophical
Transactions at the time he was doing his university
studies. His distinction was in carrying certain
directions of this work further than others.

ll5 Gowin Knight hail a mariner's compass made to his
Specification by John Smcaton. Gowin Knight. "A Description of a
Mariner's Compass." /7'46 (175(1): 505-12. on 505. John Smcaton.
"An Account of Some Improvements of the Mariner's Compass, in
Order to Render the Card and Needle, Proposed bv Doctor Knight,
of General Use," PT 46(1750): 515-17.

"'Stephen Hales, "A Proposal for Checking in Some Degree
the Progress of hires," PT 45 (174K): 277-79. At the end of this
volume of the journal, the secretary Cromwell Mortimer made an
addition to llales's paper, reporting that the engineers followed
I lales's scheme in the building they erected for the fireworks.

'"William Stukelev. "An Account of the Eclipse Predicted bv
Thales," /T48 (1753): 221-26.

""Stukeley. "An Account of the Eclipse," p. 222; fieorge
Costard, "Concerning the Year of the Eclipse Foretold bv Thales,"
/7'4K(1755): 17-26. on 19.

"''For example, this study by an Oxford Fellow draws equally
on scientific and classical texts: George Costard. "A Letter . . .
Concerning the Ages of I lomer and 1 lesiod," PT4H (1755): 441-N4.

1Z0 "Extracts of Two Letters from Father Gaubil, of the Society
of Jesus, at Peking in China." PT 48 (1753): 309-17.

CopynghleO mai

CHAPTER 3

^irst Researches

Chemistry

Cavendish entered the scientific world
gradually and methodically, with help from his
father. The earliest date in his scientific manu-
scripts is 1764, twelve years after he had left the
university and four years after he had been elected
to the Royal Society. Cavendish was then well into
his thirties.

Concerning that time of life, W illiam James
remarked in his Principles of Psychology in 1890: "In
most of us, by the age of thirty, the character has
set like plastic." 1 James's observation can be
applied to Cavendish if we take "character" to
imply a steadfast devotion to science. The ongoing
development of our subject, of which we have any
record, is of a life within science.

Cavendish's earliest work in chemistry dealt
with arsenic; he wrote a paper on it to be read, only
to be read not by the readers of the Philosophical
Transactions but by an unnamed person. 2 (One
commentator described it ominously as "Notes on
some experiments with arsenic for the use of
friends."') We suspect that the reader Cavendish
had in mind was John Hadley, nephew of the great
instrument-maker John Hadley. Hadley and William
Lewis were the only London chemists Cavendish
referred to in his first chemical writings, and
although Lewis began collecting information on
the physical and chemical properties of air at the
right time, 1765-70, 4 he could not have been his
correspondent. 5 Cavendish's reference to Hadley
was to an unpublished work by Hadley, which
Cavendish learned about first hand. 6 This work
had to do with the distillation of metals with salts,
as did Cavendish's earliest work. Hadley 's approach
to chemistry was close to Cavendish's, as we will
point out as we go along. Hadley and Cavendish
were of the same age and had been at Cambridge
together. The year Cavendish came down from
Cambridge, Hadley stayed on as a fellow of
Queen's and a colleague of John Michell. 7 In 1756,

on the recommendation of the regius professor of
physick, Russel Plumtre, Hadley was appointed
successor to Mickleburgh as professor of chemistry
in 1756. What Hadley did as professor not all
Cambridge professors did, he lectured. K Hadley
wanted a proper profession and income, and in
1758 he got permission from his college to study
medicine and hold a "Physick Fellowship." He
came to London frequently, where Cavendish saw
him at the Royal Society — Hadley recommended
Cavendish for fellowship in the Society — and at

■Paul T. Costa. Jr.. and Robert R. McCrae, "Set Like Plaster?
Evidence for the Stability of Adult Personality," in Can Personality
Change?, eds. T. F. Heatherton and J. L. Weinberger (Washington,
D.C.: American Psychological Association, 1994), 21—40, on 21-22.

■H'his earliest chemical work by Cavendish for which we have
an apparently complete record consists of the following: a bundle of
fifty-nine numbered pages of laboratory notes with index, an
unpaginated rough draft of an account of the experiments, and a
carefully written, probably final, paginated, twenty-five page version
of the account. T hese are designated, respectively, "Experiments on
Arsenic." "Arsenic." and "Kxperiments on the Neut. Arson. Salt,"
Cavendish Mss II, 1(a); II, Kb); and II, 1(c). A brief description and
analysis of these papers is given by Fdward T horpe, in Henry
Cavendish, The Scientific Papers of the Honourable Henry Cavendish,
P.R.S.. vol. 2, ed. E. T horpe (Cambridge: Cambridge University
Press, 1921), 298-301. The date Dec. 1764 appears on p. 27 of the
laboratory notes. T he unnamed reader of the work is referred to as
"you": "as you tell me you have tried yourself," and the "particulars
of this exper. which I showed you before," 1Kb): 20, 25.

'Quoted in John Pearson, The Serpent and the Stag... (New York:
Holt, Reinhartand Winston, 1983), 1 IK.

4 F. W. Ciibbs, "A Notebook of William Lewis and Alexander
Chisholm," Annals of Science 8 (1952): 202-20.

s That is evident from the way Lewis is referred to in
( lavendish's letter to his chemical correspondent.

' Hadley 's work appears in a footnote to part 4 of Cavendish's
paper on factitious air in 1766. T he first three parts were published,
the fourth withheld. "Experiments on Factitious Air. Part IV.
Containing Experiments on the Air Produced from Vegetable and
Animal Substances by Distillation." In Cavendish, Sri. Pap. 2:307-16,
on 313.

'Hadley planned to take several persons to the Royal Society for
the reading of John Michell's paper on earthquakes, but he could not
make it and asked Birch to take them instead. John Hadley to
T homas Birch, 13 Mar. /1 760/. BL Add Mss 4309. f. 3.

"John Twigg, A History of Queen's College. Cambridge, 144S-I986
(Woodbridge, Suffolk: Boydell Press. 1987), 212-13. "Hadley, John,"
DNB 8:879-80. on 879. John Hadley, A Plan of a Course of Chemical
lectures (Cambridge, 1758). Hadley gave lectures for two consecutive
years; beyond the syllabus of his lectures, Hadley published nothing
on chemistry.

144

Cavendish

the Royal Society Club. Hadley was elected to the
council soon after his election to the Society, and
one year later he offered himself as a candidate to
succeed Davall as secretary, an asset in his
profession. To this end he approached Lord
Charles Cavendish.'' Hadley enjoyed the patronage
of Hardwicke, who started him on a promising
career in medicine in London. 10 He became assistant
physician at St. Thomas's Hospital in 1760, and in
1763 he became physician to the Charterhouse and
a fellow of the College of Physicians. When
1 ladley died suddenly of fever at the Charterhouse
in 1764, at the age of thirty-three, Henry Cavendish
lost a friend and v ery able scientific colleague. His
early direction as a chemist may have owed some-
thing to this friendship."

The Royal Society was the locus of activity
for Lord Charles and Henry Cavendish, but it was
not their entire scientific world, certainly not I lenry's,
whose first researches drew on another, equally
important source, books and papers from abroad.
His first researches were in chemistry, and in the
seven years he had been coming to meetings of the
Royal Society, there had been very few reports on
chemistry and nothing of real substance. Of the
chemical authors mentioned in I ladley's syllabus of
his lectures on chemistry at Cambridge in 1758,
with the exception of the Scottish chemist Joseph
Black, they were all foreign, mostly Cerman. The
Londoner Henry Cavendish, who was just then
setting out on his chemical researches, would have
consulted foreign w ritings as a matter of course.

The gentleman's double house on Orcat
Marlborough Street, with its elegant stairs leading
off the entrance, and with its rooms used for
entertaining, was unlikely to have been used also
as a chemical laboratory reeking of fumes. Henry's
chemical researches must have been done either in
the stables or in the connected but separate
apartment on the grounds, and it probably was
done in the former. By the time Cavendish wrote
his first known paper on chemistry, he had an
elaborate chemical establishment. Since we know
that his father had chemicals, a laboratory in some
form was undoubtedly already in place for Henry.
We have no description of the laboratory, but
because of its completeness we know in general
what it had to be like. It would not have been in
the underground rooms of the separate building
behind the Cavendish house, for in the dampness

there, metals would hav e rusted, furnaces collected
mold, salts turned watery, and labels fallen off
bottles. The ground-floor laboratory room needed
openings to the outside at each end to admit fresh
air and clear away poisonous v apors. The chimney
needed to be high enough to walk under and wide
enough to walk in front of. Located underneath the
chimney were various furnaces and probably a
double bellows to fan the flames from gentle heat
to red hot. Ready at hand, suspended on hooks,
were pokers, pincers, tongs, shovels, and pans,
much as in a kitchen of the day. Near the chimney
was an anvil along with hammers and a range of
other tools. Lining the walls were shelves for
chemicals and various other supplies. Bins were
there to store bulk charcoal, sand, and quicklime.
Since acids, alkalis, metals, and earths were as pure
as possible, standing in a corner of the laboratory
was a lead or stone "fountain" with a drain pipe,
where vessels were cleaned after each use, no
doubt by an "assistant." Housekeeping was of the
essence of good chemical practice. In the center of
the room there would have been a big table for
chemical operations not requiring a high heat. On
it, we suppose, were scales, mortars and pestles,
filtration paper, corks, stirrers, and, not least,
pencils, pens and ink, and a stack of small sheets of
paper for keeping notes of what was done as it was
done. 1 ' From Cavendish's manuscripts, we can be
specific about what he required to carry out his
researches on his first substance, arsenic. To make
the chemical reactions go, he used heating lamps, a
furnace-forge, and a reverberator furnace (designed

'Hadley's lather asked for Birth's support. Henry Hadley to
Thomas Birch, 13 Oct. 1 759. BL Add Mss 4309, f.l. Hadley told Birch
and Charles Cavendish of his desire to become secretary. Thomas
Birch to Philip Vorke, 13 Oct. 1759. BL Add Mss 35399, f. 115.

'"I ladley wanted I lardwickc's help in getting a job at St.
Thomas's, recalling "so many advantages last year in a similar
pursuit" he had received from Hardwicke. John Hadley to Lord
Hardwicke. 1 Jan. 1760, Id.. Add Mss 35596. f. 73.

""Hadley," D.XH K:K79. We cannot be certain, of course, that
Cavendish's correspondent was Hadley. The next possibility is Lord
Charles Cavendish, the next William Heberden. Lacking direct
evidence, we still think it likely that the person was Hadley.

'-'We have been guided in our sketch of Cavendish's laboratory
by the entry "Laboratory (Chemical)" in Pierre Joseph Macqucr's
chemical dictionary, the first of its kind, published in 1766. just after
Cavendish began his experiments. A Dictionary of Chemistry.
Containing the Theory and Practice of Thai Science: Its Applications to
Natural Philosophy. Natural History, Medicine, and Animal Economy,
trans. J. Kier. Z vols. (London, 1771). Macquer's laboratory was
intended for the "philosophical chemist." and with its list of
reagents, it sufficed for performing "any chemical experiment."

Cooyrlghled malar

First Researches

145

to direct the flame back on the heated substance),
which he placed high into the chimney because of
the "obnoxious" fumes. There was a sand pot for
distilling at "sand heat" and for holding bottles.
Heat entered into most of his operations: roasting,
calcining (changing a substance to a calx, or powder),
dissolving, distilling, subliming, and evaporating.
His other operations included precipitating,
crystallizing, filtering, deliquescing, and weighing.
We assume that from the start, Cavendish's scales
were of good quality, since for him weighing was
the method of chemical precision. Cavendish had
at hand an elaborate collection of containers, some
metal, some earthen, most glass. There were open
flasks, Florence flasks (having long, narrow necks),
retorts (having downward bending necks for
distilling), receivers (flasks for retaining condensates
and distillates), adaptors (for connecting retorts and
receivers), bottles for holding everything, pipkins
(small pots and pans), and copper pipes. There was
a lead crucible for keeping the bottom of another
crucible placed in it cooler than the top of it, a kind
of inverted double-boiler. There was another
crucible, designed and drawn by Cavendish, for
use in the reverberator furnace, complete with a set
of aludels (pear-shaped pots open at the bottom as
well as the top and made to fit over one another for
subliming). All of this apparatus was made for the
purpose, to which Cavendish added a make-do,
humble coffee cup for calcining. The reagents that
Cavendish performed his operations with and filled
his flasks with were many, mostly solvents, various
acids, solutions of various metals in acids, testing
solutions and treated papers for acids and alkalis,
various alkalis, and a few neutral salts among other
things. u Cavendish's experiments on arsenic-
depended on a sizable investment in chemical
apparatus and supplies.

The incentive for Cavendish's researches
on arsenic (arsenious oxide) is unknown, but we
know that his starting point was Pierre Joseph
Macquer's discovery and naming of "neutral
arsenical salt" (potassium arsenate), which appeared
in two papers of the Paris Academy of Sciences
Memo} res in 1746 and 1748. 14

If, as we suggest, Cavendish wrote up his
experiments on arsenic for John Hadley to read, we
can point to Hadley's Cambridge lectures as proof
of his interest in Macquer's experiments on the
neutral arsenical salt. 15 In this the most important

of his early work, Macquer distilled arsenic with
nitre (potassium nitrate) and analyzed the residue,
a compact, white, soluble, and mild salt. He noted
that arsenic itself behaved like an acid, but he did
not discover the acid of arsenic, which was left for
Cavendish to do. The discovery of the acid was
important at the time, since few acids were known,
and each was a valuable reagent for the chemist.
The discovery of the new salt was important, too; it
had obvious value for philosophical chemistry, and it
had practical uses, though Macquer thought that
these did not include medicine, despite its actual
mildness, since the "name of arsenic is so terrible." 16
Like electricity, chemistry carried risks. The
expansive power of air occasioned violent explosions,
putting life and limb in jeopardy. Spilled acids ate
"away the skin." In 1767 a paper appeared in the
Philosophical Transactions on a new distilling apparatus
that spared the chemist's lungs from harmful fumes. 17
And there were deadly poisons, like arsenic, the
agonizing symptoms and fatal consequences of
which were noted in every book of chemistry.

"In his study of arsenic. Cavendish used a Rood many rcagants,
which were, in his words and spelling, and with modern names in
parentheses: distilled vinegar, spirit of salt (hydrochloric acid), oil of
vitriol (sulphuric acid), spirit of nitre (nitric acid), aqua fortis
(concentrated nitric acid), nitre, syrup of violets (test), toumsol paper
(test), blue vitriol (copper sulphate), green vitriol (ferrous sulphate),
solutions of silver, mercury, copper, and iron in nitric acid, solutions
of mercury, copper, and iron in concentrated nitric acid, solutions of
tin in hydrochloric acid, solutions of gold and nickel in aqua regia
(mixture of nitric and hydrochloric acids), solution of regulus of
cobalt, sopc leys (potassium hydroxide), pearl ashes (potash), a fixed
alkali (potassium carbonate), calcareous earth (whiting, or carbonate
of lime), volatile alkali (ammonia), magnesia, earth of alum, sedative-
salt (boric acid), white flux, sulphur, linseed oil, and charcoal.
Cavendish also had at hand pure, "rain" water.

H Pierrc Joseph Macquer, "Researches sur larscnic. Premier
memoir." and "Second memoire sur I'arsenic," Memoirs de I' Academic
Royale des Sciences, 1746 (published 1751), pp. 233-36, and 174H
(published 1752), 35-50. Macquer later described this work in 1766
in his Dictionary of Chemistry. The article "Neutral Arsenical Salt" is
in vol. 2, pp. 666-67. Shortly before Cavendish's researches on the
subject, Macquer's work was described in English in an annotation
by William Lewis to his translation of Caspar Neumann, The Chemical
Works . . . Abridged and Methodized. With Large Additions. Containing the
Later Discoveries and Improvements Made in Chemistry and the Arts
Depending 'thereon (London. 1759), 143.

"The full lectures for which Hadley published the syllabus are
preserved in manuscript in the library of Trinity College. They are
discussed in L. J. M. Colcby, "John Hadley, Fourth Professor of
Chemistry in the University of Cambridge." Annals of Science 8
(1952): 293-301; Hadley's lecture dealing with Macquer's neutral
arsenical salt is mentioned on 301.

"'Macquer, Dictionary. 100, 666-67.

l7 Peter Woulfe, "Experiments on the Distillation of Acids.
Volatile Alkalies, etc. Shewing How They May Be Condensed
without Loss, and How Thereby We Mav Avoid Disagreeable and
Noxious Fumes." PTS1 ( 1 767): 517-34.

146

Cavendish

Arsenic, the great German chemist Caspar
Neumann wrote, is a "most violent poison to all
animals," so that the "utmost caution is necessary
in all operations upon arsenic, to avoid its fumes,"
which have a "strong fetid smell resembling that of
garlic"; its solution has a nauseous taste; arsenic, it
seemed, had no redeeming features. It was little
wonder that this mineral, as Neumann said, had
been "so little examined" by the chemists. At the
time Cavendish made his study of arsenic
compounds, chemists still had not been able to
"determine what it /arsenic/ really is, or to what
class of bodies it belongs." 1 " Independently of, but
befitting, its noxious properties, arsenic, Macquer
said, has other "singular properties, which render it
the only one of its kind." Neither fish nor fowl, but
something of a flying fish, arsenic behaves like a
metal in some states and like a salt in other states.
On the one hand, like every metallic calx, arsenic-
can be changed into a metallic form, a "true
semimetal," or "regulus of arsenic." The means of
doing this for Macquer is to combine the calx with
"phlogiston," the all-important substance or
principle in the chemistry of Cavendish. On the
other hand, like salts, arsenic is soluble in water.
Kven when regarded as a salt, arsenic is an
uncommon thing, neither acidic nor alkaline, yet,
Macquer claimed, behaving as if it were an acid. 1 ''
The "vers' singular and extremely different"
properties of arsenic had led Macquer to his
investigations of this little studied calx in the first
place.-" In other ways than by its dual nature,
arsenic differs from other known calces: it is
volatile with a strong smell, it is fusible, it unites
with metals and semimetals, and — the difference
that Macquer and Cavendish picked up on — it
decomposes nitre when distilled with it.' 1 From
the standpoint of affinities (the readiness to unite
with other substances), arsenic is exceptional too. 22

Although Cavendish did not tell us why he
investigated arsenic, from the state of chemistry at
the time, we get an idea of its considerable interest
for him. The substance was at once dangerous,
difficult, unique, and scientifically puzzling. 2 ' Its
study demanded manipulatory and analytical skills
of a high order, a stiff challenge and testing ground
for a young chemist of genius.

In practice, chemistry was a complicated
art, since it dealt with all kinds of matter and with a
large repertoire of operations. In principle.

chemistry looked simple, though this appearance
was changing. Chemicals were put in classes and
the outcomes of their combinations were put in
small, tidy tables. Neutral salts, Cavendish's
starting point, are a case in point. These were salts
composed of acids and other substances, mostly
alkalis, that were without acidity. Not long before,
all of the known neutral salts could be listed in a
table of twelve entries, which corresponded to the
possible combinations of the four known acidic-
salts and the three known alkaline salts. Just as
Cavendish began to work with these salts — in his
arsenic experiments, with the acidic salt "arsenic,"
the alkaline or vegetable salt "nitre," and Macquer's
new neutral salt of arsenic — the tidy, manageable
table of neutral salts was fast expanding. 24 The
empirical field of salts was recognized as highly
undeveloped, so many salts "little known, or not
even thought of." 25 Cavendish procured Macquer's
neutral salt using Macquer's method of distilling
arsenic with nitre, producing copious red fumes
and leaving behind a cake of neutral arsenical salt.
He then tried another way, dissolving arsenic in
spirit of nitre, then adding pearl ashes to it to
obtain neutral arsenical acid. He had made a
discovery: what combined with the alkali to form
the neutral salt was an acid, but not any known
acid, a new acid, "arsenical acid" ("if you w ill allow
me to call it by that name"). 2 '' The change that
arsenic underwent in distilling and dissolving (and

'"Neumann. Chemical Worts, 140—41. 14.S. What Neumann,
Macquer, Cavendish, and their contemporaries called "arsenic" is a
dense, brittle substance with a crystalline or vitreous look; this
substance, arsenious oxide, is a common by-product of roasting
metallic ores. Another name for it then, as now, is "white arsenic," the
calx of regulus of arsenic, the white, shiny semimetal.

l9 Macqucr, Dictionary 2:634.

-'"Pierre Joseph Macquer, Elements of the Theory and Practice of
Chemistry, trans A. Reid. 2 vols. (London, 17.SH) 1:%.
-''Macquer, Dictionary 1:99-100.

"Arsenic has the least, or next to least, affinity of the soluble
substances for the several acids, with the exception of aqua regia.
Gellert's "Table of the Solutions of Bodies." at the end of vol. 2 of
N 1 acq uc r. Dictionary.

23 Arsenic was soluble in acids, and the results had "not yet been
sufficiently examined." Macquer, Dictionary 1:103.

24 The Scottish chemist William Cullen's table of twelve neutral
salts was reproduced in Donald Monro, "An Account of Some
Neutral Salts Made with Vegetable Acids, and With the Salt of
Amber; Which Shews that Vegetable Aeids Differ from One
Another . . .," PT 57 (1767): 479-516. Monro, 483, pointed out that a
table had been published in Germany giving three or four more of
these salts, and that there were actually many more because vegetable
acid was in reality many acids each with its own neutral salts.

25 Macquer, Dictionary 2:642, 649.

-'Cavendish, "Arsenic," Cavendish Mss II. Kb): 10.

Copyrighted m aerial

First Researches

147

calcining) made it acidic: neutralizing alkalies and
so on, this new substance had "all the properties of
an acid," which conclusion Cavendish qualified
with an implicit acknowledgment of the fatal
reputation of arsenic, "unless perhaps it should fail
in respect of taste which I have not thought proper
to try." 27 This discovery was the high point of
Cavendish's researches on arsenic.

In the history of science Cavendish is
invariably remembered as the man of quantity.
Although it is a caricature, he was that too, a man
who frequently made quantitative observations in
pursuit of scientific understanding. His laboratory
notes arc filled with numbers, standing for weights,
expressed in ounces and their breakdown into
drams and grains. Other numbers stand for specific-
gravities, the index of concentration. Other numbers
stand for proportions of reactants; Cavendish spoke
of "saturation," a term in use for the point at which
acids in combination with other bodies lose their
acidity, and also a term used to describe solutions
in which a solvent has dissolved as much of a
substance as it can. Cavendish's skill in quantitative
work is fully evident in this early chemical
research. He worked with uncommonly small
quantities of substances, ounces instead of the
familiar pounds, the mark of a skilled chemist. In
doing an experiment, he usually began with
carefully measured quantities of substances, which
he then combined and performed operations on,
and the products he obtained he would again
weigh. Having once obtained the products,
however, he would put them through a series of
tests, "small experiments," as he called them, in
which he did not record, and probably did not
measure, the quantities involved. Quantity had the
same place in this work as did any quality,
perceived by sight, smell, or taste. In the detective
work on neutral arsenical salt, measurements and
descriptions alike gave Cavendish clues about what
was going on in the fumings and the shootings of
crystals; that is, about what went in and what came
out.- 8 To the extent that there was a difference
between weighing and seeing, the former could be
more accurate than the latter: "as well as could be
judged by the eye," Cavendish wrote of one
arsenic observation, a kind of qualification he did
not make about weighing. In this chemical work,
Cavendish's senses were fully engaged, and he
described his sensations with a discriminating

vocabulary. With colors, he made the most
distinctions: milky, cloudy, yellow, pale straw,
reddish yellow, pale madeira, red, reddish brown,
dirty red, green, bluish green, pearl color, blue, and
transparent, turgid, and muddy. By smell, he
distinguished between the various acids and their
products. He observed the degree of heat, the
strength of effervescence, the speed of dissolution,
the shape and size of crystals. He observed textures:
dry, hard, thin jelly, gluey, thick, stiff mud, lump.
No poet paid greater attention to his sensations
than Cavendish did to his. His notes on arsenic-
were the journal of a complete man — whose whole
being was, just then, concentrated on arsenic.

Under "complete," we include the thinking
man, one whose final goal was experimental results
together with understanding. In the final writing of
Cavendish's researches on arsenic, the longest
section by far, roughly half of the whole paper,
consisted of a combination of conjectures and
experiment. It is to be expected that they were
combined, since by then, a priori theoretical
conjectures in chemistry were not regarded as the
way to advance knowledge of the various
substances of which the world is made. 29 Cavendish
presented his experiments first, but his theoretical
ideas did not arise inductively from them. They
came from the same place his problem of arsenic-
did, from the chemical literature of his day.

Chemistry in the middle of the eighteenth
century was still closely tied to pharmacy,
medicine, metallurgy, and manufactures. It also
had a philosophical content, with two sources. One
was German, associated above all with Georg Stahl
and his predecessor Johann Becher. Stahl gave the
name "phlogiston" to the oily earth given off in com-
bustion and presumed present in every combustible
body. Phlogiston was one of four elements of Stahl's
chemistry (the other three being water, mercury, and
another kind of earth), but because of its ubiquitous
presence in chemical processes of interest, his chem-
istry came to be known by the name phlogiston. ,u

"Ibid. II. Kb): 13.

2B Henry Guerlac characterizes chemistry as a qualitative science
using quantitative techniques in "Quantification in Chemistry," his
52 (1961): 194-214, on 196.

2 ''A. M. Duncan, "Some Theoretical Aspects of Eighteenth-
Century Tables of Affinity— I," Ann. ofSci.\% (1962): 177-94, on 185.

M Stahl developed the explanation of combustion of J. J. Becher,
who worked in the second half of the seventeenth century.

148

Cavendish

Phlogiston entered Stahl's explanation of not only
combustion but of acidity, alkalinity, chemical
combination, and even colors and smells. Matter is
composed of aggregated particles according to
Stahl, but his chemistry is distinctly chemistry, not
physics. The other philosophical source was
associated with Boyle, Newton, and Boerhaave,
who regarded chemistry as a branch of physics.
After Newton, those who approached chemistry in
this way thought that chemical substances attracted
one another in analogy with the mutual attraction
of the earth and the moon. There were unsuccess-
ful attempts to express this understanding mathe-
matically, but for the most part, chemists used it
only as a guide in their researches, which they
conducted experimentally. Cavendish adopted the
physical approach to chemistry, which by this time
had incorporated the combustible principle,
phlogiston, from Stahlian chemistry. It is under-
standable that it was Macquer who served as
( .avendish's guide in chemical research, for
Macquer was at once a proponent of phlogiston, a
Newtonian, and an advocate of weighing in
chemistry, who believed that weighing was a likely
starting point for the ultimate mathematical
development of chemistry. His text on theoretical
chemistry in 1749 was one of the earliest to present
chemistry as a science instead of recipes, and it was
the principal publication in the adoption of the
phlogiston theory in France. 31 It was customary for
chemists to divide their science into a theoretical
and a practical part; Stahl and Boerhaave had done-
it, so did Macquer. Macquer's down-to-earth,
complementary text on practical chemistry in 1751
together with his earlier text on theoretical chem-
istry were brought out together in 1 75S in an
English translation, which found a receptive
audience in Britain. 3 - Macquer emphasized the
leading concept of the physical approach, affinity,
popularizing the term, in place of the earlier
"attraction"; in his Dictionary of Chemistry in 1766,
he suggested that affinities could be treated
quantitatively, which they later were. In these
several ways, Macquer was important in giving
shape to the chemistry that Cavendish endorsed
from the beginning and built upon thereafter."

At the time Cavendish took up chemistry,
the phlogiston theory had long been familiar in
Germany, but in France and Britain it was just
taking hold.* 4 William Lewis's translation in 1759

of the writings of Caspar Neumann, one of Stahl's
school of chemists in Berlin, was the first account
of the phlogiston theory in Fnglish. ,s Neumann's
book is practical, filled with straightforward
descriptions of operations and reactions, with little
that is quantitative, nothing about air, and short on
theory; but phlogiston is there, the "inflammable
principle," the unitary principle, the same in one
metal as in another, in other bodies as in metals, in
the vegetable and animal as well as the mineral
kingdoms. v ' At the heart of the theory was a
unified explanation of combustion and of the
calcination of metals (their transformation to
powder, with properties of an earth). Metals, like
ordinary combustibles, contain phlogiston in
combination with another part, and as when
combustibles are burned their phlogiston separates
from the other part and flies off, when metals are
dissolved in acids they likewise lose their
phlogiston. The evidence of phlogiston in flight
was obvious to the senses: flame and fumes, sight
and smell. The experimental proof of phlogiston
seemed incontrovertible, which is why the physical
school of chemistry needed it as well as the
Stahlian: if a metal is deprived of its phlogiston by
an acid and reduced to its calx, the pure metal can
be restored, if sometimes with great difficulty, by
combining the calx with an inflammable substance
from which it extracts the lost phlogiston. Fither by
its presence or its absence, phlogiston determines
most chemical reactions, and by keeping a balance
sheet on phlogiston, the chemist could foresee the
outcome of chemical processes. However, indis-
pensable as phlogiston was as a chemical concept,
the thing itself was elusive. Phlogiston could not
be isolated and studied in itself (though for a time
Cavendish believed that it could be); it was the

''Duncan, "Some Theoretical Aspects of Eighteenth-Century
Tables of Affinity." 190.

I2 W. A. Smeaton, "Macquer, Pierre Joseph," DSB 8:618-24, on
614. Macquer's Elemens de chymie thiorique (Paris. 1749) and Element
de chymie pratique (Paris, 1751) were brought out in English transla-
tion by Andrew Ried in 1758 as Elements of the Theory and Practice
o f Chemistry.

"Smeaton, "Macquer," 620-21. Maurice Crosland, "The
Development of Chemistry in the Eighteenth Century," Studies on
Voltaire 24 (1963): 369-441. on 397-98.

"Thomas I.. Nankins, Science and the Enlightenment (Cambridge:
Cambridge I niversity Press, 1985), 95.

ls Nathan Sivin, "William Lewis (17(18-1781) as a Chemist,"
Chymia 8 (1962): 63-«8, on 73.

'"Neumann. Chemical Worts, 53.

Copyrighted material

Firsr Researches

149

"least accurately known" of all chemical substances
or principles."

Although within Stahlian chemistry affinity
was a useful concept, by the time of Lewis's
translation of Neumann's text, affinity was
principally associated with Newtonian attraction
and the physical school. "Affinity," Lewis wrote, is
the name for chemical attraction, which takes place
at insensible distances. The union of one chemical
substance with another could be broken by bring-
ing up a third substance with an affinity for one or
the other substance greater than they have for one
other. The concept of affinity provided chemistry
both with a philosophical foundation in Newtonian
attraction and an ordering at the practical level: it
told if am particular chemical substitution did or
did not take place. Tables of affinity had been
introduced early in the century, but they were
widely taken up only about the time of
Cavendish's first researches. Ultimately, tables of
affinity did not fulfill their early promise of leading
to the general laws of chemistry; other avenues led
to that, considerably later. 58

The distinction between what Cavendish started
with, arsenic, and what he ended with, arsenical
acid, he understood with the aid of phlogiston.
"The only difference" between the two, he said, is
that the acid "is more thoroughly deprived of its
phlogiston." 1 '' Identifying arsenic with other
"metallic substances," which by the phlogiston
theory are rich in phlogiston, he accounted for the
changes arsenic undergoes in becoming the neutral
salt and the acid by the readiness with which spirit
of nitre unites with phlogiston. 40 So convincing was
the phlogistic explanation to ( iavendish — or, looked
at another way, so dependent then was chemistry
on phlogiston — that Cavendish bent the theory
repeatedly to accommodate it rather than bring it
into question. 41

Cavendish's extensive researches in
chemistry were carried out entirely within the
framework of phlogistic arguments, which for most
of that time were also subjected to critical and,
ultimately, fatal examination by Lavoisier. Cavendish's
junior by ten years though entering into his
researches only slightly after Cavendish, Lavoisier
denied the existence of phlogiston, and in its place
he offered explanations in terms of oxygen.
(Cavendish's later researches would contribute

substantially, if unintentionally, to Lavoisier's
successful attack on phlogiston.) In Lavoisier's
route to his understanding of the role of oxygen, he
gave great attention to acidity, "oxygen" meaning
acid-forming. 4 - Acidity was a principal issue
between the defenders and the opponents of
phlogiston, and neither got it right. Before that
issue was joined, Cavendish discussed the action of
acids in what was to be his only theoretical writing
on phlogistic chemistry. In it he showed the power
of phlogistic reasoning without yet having to
defend it, but his reasoning, while useful in his
understanding of chemical reactions, was tentative,
and he did not publish it. If he had, Lavoisier
would have had to answer it, since it was by a
chemist worthy of refutation. Ultimately, as we

''Thomas Thomson. The History of Chemistry, vol. ' (London.
1831 ), 250-63. Macqucr, Dirtiontiry 2:516.

'"William Lewis, Commerrium Philosophiae-Tcchnicum; or. The
Philosophical Commerce of Arts: Designed us an Attempt to Improve Arts,
Trades, and Manufactures . . . (London. 1763), iv-ix. Lewis was one of
the first to advocate the use of affinity tables, including a
modification of the original Geoffroy's tabic in his .Wn" Dispensatory
in 1753. Duncan, "Some Theoretical Aspects of Kightccnth-Century
Tables of Affinity," 178-79, 232.

''Cavendish, "Arsenic," Cavendish Mss II, I (b): 16. Cavendish
made the acid or the same thinfi, in effect, the neutral arsenical salt,
three ways: distilling arsenic with nitre, dissolving nitre in
concentrated nitric acid, and heating arsenic with fixed alkali. All
three methods had the same rational: the effect of exposing a metal
(for that is how he regarded arsenic) to an acid or to heat and open air
« as to deprive it of its phlogiston.

■"'Macqucr wrote: "Nothing can equal the impetuosity w ith w hich
nitrous acid joins itself to phlogiston." Dictionary of Chemistry 1:11.

■"Here are two examples. I) Cavendish distilled the product of
arsenic and aqua fortis, obtaining a residue, or "caput mortuum. "
which he weighed. By the standard phlogiston theory, the caput
mortuum should weigh less than the arsenic because of the
phlogiston driven off, but Cavendish found that his caput mortuum
weighed more. He attributed the excess weight to water acquired by
the arsenic from the aqua fortis. It is the kind of explanation
Cavendish and fellow upholders of the phlogiston theory would give
for this frequently encountered excess weight. The oxygen theory, of
course, had an explanation for this excess, the addition of oxygen.
2) Cavendish's hypothesis that arsenic acid is arsenic deprived of
phlogiston suggested to him another, simpler method for making the
acid. He designed a crucible luted to aludels and placed it in the
reverberator furnace, subliming arsenic exposed to a current of air.
He expected that phlogiston would be driven off and attach to the
air and that what remained behind would be arsenic deprived of
phlogiston, namely, arsenical acid. But he found that the sublimed
arsenic was nothing other than pure arsenic. This failure did not
discourage him; it did not invalidate the hypothesis. To Cavendish it
only meant that sublimation is less effective than the other methods
in getting arsenic to part with its phlogiston. Cavendish's reasoning
in both of these examples seems slippery, but it does only in
retrospect, after the success of the oxygen theory.

^Historians of chemistry have recently come to appreciate the
importance of the problem of acids in Lavoisier's work; earlier their
attention was directed mainly toward Lavoisier's approach to the
problem of combustion. This change is summarized in William II.
Brock, The l'ontana History of Chemistry (London: I'ontana, 1992), 125.

150

Cavendish

know, it would only have strengthened Lavoisier's
case. In brief, Cavendish's theory of the "solution
of metals in acids" was that all metals are deprived
of phlogiston by acids and that the reactions are the
result of affinities. To encompass mercury and the
noble metals alongside the ordinary ones w ithin his
general theory, Cavendish had to engage in some
tangled reasoning. 41 What is of enduring interest here
is that Cavendish, in his first researches, already
revealed himself as the seeker of general laws.

Chemistry emerged as a science in the
eighteenth century with the development of
pneumatic chemistry and analytical chemistry. 44
Cav endish's place in the history of chemistry is in
pneumatic chemistry, and although he came to it
through analytical chemistry, in his analysis of
arsenic. Cavendish had already revealed himself as
a close observer of air. "Air," "effervescence,"
"vapors," and "fumes" are words that appear
throughout his account. Air, as Stephen Hales and
Joseph Black had shown, is a chemically active
substance, and referring to "air" as just another
constituent that passes from substance to substance
and sometimes flies off. Cavendish took into
account the weight of air in his quantitative analysis
of neutral arsenical salt. Although air was an
essential consideration in Cavendish's analysis, he
did not yet collect it and study it in its own right.

If Cavendish had published his researches
on arsenic, he would have come before the world
as an accomplished analytical chemist. But, as we
have said, he did not write up his researches for
publication but for a friend, who was a chemist and
working on related problems. In going from the
draft to the actual letter, or a copy of it. Cavendish
made revealing changes in wording. Whereas in
the draft he expressed his opinions, such as his
differences with Macquer forcefully, in the final
draft he left much of the forcefulness out or toned
it down. Kven in the semi-privacy of a corre-
spondence, this man of strong feelings was guarded.

As it was, arsenical acid became known to
the chemical world at large through a publication in
1775 by the Swedish chemist Carl Wilhelm
Scheele, who became celebrated for his discoveries
of this and other acids. That Cavendish's work was
unknown is borne out by Scheele's remark that he
did not know of any work on arsenic since
Macquer's. Scheele's numerous experiments were
less quantitative than Cavendish's, but the reasoning

behind his experiments was much the same:
arsenic contains the "inflammable principle,"
phlogiston, which can be separated from it by nitric-
acid, leaving behind arsenic acid. 4S

Before we discuss Cavendish's first
publication in chemistry two years later, we need
briefly to discuss the one other early chemical
research of his, done probably about the same time
as his research on arsenic. This research was on
tartar, 46 a deposit found on the sides of casks of
wine, a hard, thick crust, red or white depending
on the color of the wine. When crystallized by-
evaporation, it forms another crust, "cream of
tartar," an acid. Cavendish's interest seems to have
been in determining the amount of alkali in this
acid, cream of tartar (potassium hydrogen tartrate),
and in the soluble tartar (normal potassium
tartrate). The stimulus no doubt was a publication
in 1764 by the German chemist Andreas
Sigismund Marggraf, who showed that tartar,
despite its reputation as an acid, contains an
alkali. 47 Like arsenic, then, tartar had what seemed
to be contradictory properties, and we suppose that
Cavendish was drawn to investigate these specific-
substances for the similar problem they posed. He
was drawn to the chemists who worked on these
substances too for the kind of work they did in
general. In the case of arsenic it was Macquer, in
the case of tartar, Marggraf. Caspar Neumann's
pupil, famous for his precision, Marggraf has been
called the originator of chemical analysis. 4 * Once
again, John Hadley suggests himself as Cavendish's

4, \Villiam Lewis, one other chemical author besides Macquer
cited by Cavendish, in the previous year. 1 763, had published a book
on practical chemistry, in which he said that when gold is dissolved
in aqua regia (nitric acid mixed with hydrochloric), the nitric acid
tlics off. Commercium Philosophico-Technlcum, 99. This observation
enabled Cavendish to include even gold in his general rule that nitric
acid dissolves metal readiest and yet has least affinity to metals. Not
gold but the phlogiston of gold unites with the nitric acid, which
comes off as vapor. Like gold, arsenic is deprived of its phlogiston
only by nitric acid.

44 Crosland, "The Development of Chemistry," M\.

-^Karl W ilhelm Scheele. The Chemical Essays of Charles-William
Scheele, trans, with additions by T. Beddoes (London, 17K6). 14.}— to.

""'Cavendish did two sets of experiments, describing them on
numbered sheets: "Old Lxpcrt on Tartar," 10 ff, and "New Kxper.
on Tartar," 24 ff. plus h more sheets. Cavendish, Sci Mss II, 2(a) and
2(b). respectively.

47 Thorpe, in Cavendish, Set. I'up. 2:301. Cavendish discovered
the true nature of cream of tartar and its relationship to soluble tartar:
J. R. Partington. A Short History of Chemistry, 2d ed. (London:
Macmillan. 1951), 104.

4s Called that by Thomas Thomson, quoted in J. R. Partington,
A History of Chemistry, vol. 2 (London: Macmillan, 1%1 ), 724.

Copyrighted maier

First Researches

151

correspondent. A great admirer of Marggraf, Hadley
in his Cambridge lectures said that Marggraf was
the master of his science, the "most uncommonly
Eminent whether we consider his ingenuity in
Contriving, his practical Skill in conducting his
Experiments, or his Sagacity and judgment in the
Conclusions he draws from them." 4 '' Like arsenic,
tartar was a fantastic substance, though in its own,
very different way. The spectacular effects of
experimenting on tartar were remarked on by
every chemist who wrote on the subject, including
Hadley, who discussed Hales's production of "fixed
air" from the action of acids of tartar; 5 " according to
Hales, fully a third of the weight of tartar was lost
in the air it gave off. 51 So powerful was the release
of air that the vessels used in the distilling burst
into shivers. 52 It has been suggested that Marggraf
gave Scheele the idea of making tartaric acid. In
any case, Cavendish again did not publish his work
but left the analysis to Scheele, who made tartar
the subject of his first, memorable paper. 53 Given
the conspicuous presence of air in tartar and its
compounds, in his chemical analysis of tartar
Cavendish was halfway to pneumatic chemistry.

Before Cavendish appeared in print under
his own name, an example of his chemical analysis
appeared in a paper by William Heberden.
Heberden was himself highly knowledgeable in
chemistry, having lectured on it in connection with
medicine at Cambridge, but in this examination he
deferred to a superior, if still unknown, chemist,
Cavendish. Heberden's brother, Thomas, had
collected a fossil alkali from the lip of a volcano, a
place where brimstone might be expected but not
a salt like this. From experiments "made and
communicated to me by the Hon. Henry Caven-
dish," Heberden laid down, and set off in quota-
tion marks, a set of propositions about the salt in
question. Cavendish found that this salt differed
from the vegetable alkali in that it crystallized
without the addition of "fixed air," and here, in a
footnote, he cited Blacks experiments on magnesia
alba, the famous experiments on fixed air, which
together with Hales's earlier experiments on air
released from bodies, provided the foundation of
eighteenth-century pneumatic chemistry. In this
chemical examination of a mineral for his friend
Heberden, Cavendish may have been encouraged
to begin, if he was not already set upon, his course
as a pneumatic chemist. 54

At this point we need to discuss Blacks
work. Cavendish's senior by three years, Black in
1756 published an enlarged, English version of his
medical thesis at the I'niversity of Edinburgh,
"Experiments upon Magnesia Alba, Quicklime,
and Some Other Alcaline Substances." The origin
of this, Black's only major publication, was
practical, the medical problem of urinary-tract
stones. In it Black dealt briefly with the medical
virtues of magnesia but mostly with its chemistry.
At age twenty-seven, already a master of the
chemical art, Black had an advantage that
Cavendish did not, a great teacher of chemistry in
William Cullen, who regarded chemistry as a
science with laws as fixed as those of mechanics.
Black informed himself of the wider world of
chemistry, and like Cavendish, he looked to
Marggraf for inspiration, a reason for, or a reflection
of, the closeness of Black's and Cavendish's work
in general. Black told Cullen that he would rather
have written what Marggraf had written than
anything else in the library of chemistry. Black
showed his knowledge of the chemist's standard
practice, determining, for example, the place of
magnesia in Geoffroy's table of affinities, but his
originality in chemistry began with his observation
that when subjected to fire, magnesia lost a great
proportion of its weight and that the lost portion
was air. His experiments on magnesia led him to
the nature of quicklime, that most caustic of
substances. The causticity is inherent in alkali,
Black concluded, made manifest when the alkali is
deprived of its air. He showed that this same air,
"fixed air" (not an original term), is found in other
alkalis and that it is different from common air.
Like Hales, whom he acknowledged, (and like

«*Coleby, "John 1 ladlcy," 295.
s "Ibid. 298.

5, Antoine Baumc, Manual de rhymie, on expose ties operations el des
produits d'un routs de chjmie. Outrage utile aux personnes qui veulenl
suivre un fours de rette science, on qui out dessein de se former un cabinet de
rhymie (Paris, 1763), 392.

s 'Antoine Laurent Lavoisier, Essays on the Effects Produced by
Various Processes on Atmospheric Air; ailh a Particular Virtr to an
Investigation of the Constitution of the Acids, trans '1". I lenrv (Warrington,
1783). 7.

"Partington, History Z:72 l ). Thomas Thomson, The History of
Chemistry, 2 vols. (London, 1830), 2:63.

,4 William Heberden, "Some Account of a Salt Found on the Pic
of Teneriffc," FT 55 (1765): 57-60. This paper was read at the Royal
Soeiety on 7 Feb. 1764. In his analysis. Cavendish mentioned
vitriolated tartar, which eonneetcd with his independent study
of tartar.

152

Cavendish), Black did not begin his investigation
with air but concluded with it. Like Hales and
other chemists, he had observed that in their
operations, "part of a body has vanished from their
senses," anil he intended to study this vanishing
part, air, in itself, but he did not, leaving it to
Cavendish and others. More than anyone before
him. Black used the chemical balance to
advantage, and in this too Cavendish was to follow
in black's footsteps. 55

Chemistry had its unifying concepts, one of
which was phlogiston, the inflammable principle,
and another was acid: it was thought that there
might be only one acid, or Stahl's "saline princi-
ple," v itriolic acid, of which the others were modifi-
cations. 56 Likewise, there might be only one solvent,
water. 57 There was definitely only one air: it was one
of the four elements or principles, which cannot be
resolved into others, the others being earth, water,
and fire.™ In the course of the eighteenth century,
chemistry would become more complex before it
would become simpler again. Cavendish's first
publication would reject the notion of a single air.

Air is Cavendish's subject, as he made clear
in the opening sentences of his first publication, in
1766, "Three Papers, Containing Experiments on
Factitious Air." The usual meaning of "fixed air"
was any sort of air (or "gas," a contemporary word
Cavendish did not use) contained in bodies;
Cavendish had a specific meaning for it, the air by
that name, which Black had studied. Since it was
only one species of "fixed air," to avoid confusion
Cavendish replaced it by Robert Boyle's word,
"factitious." By "factitious air," Cavendish
understood "any kind of air w hich is contained in
other bodies in an inelastic state, and is produced
from thence by art." s< ' The first factitious air he
described was new, but the name he gave to it,
"inflammable air," was not. "Inflammable air" is a
descriptive term — for it is our inflammable gas
hydrogen — and it also corresponds to Cavendish's
identification of it with the "inflammable" principle
or substance, phlogiston. Cavendish's discrimination
between different factitious airs in this first paper
was the beginning of a concerted search by
chemists for new kinds of air (gases); over the next
ten years, a do/en would be discovered, by
Cav endish and by others who followed. 60

Cavendish found that three metals (zinc,
iron, and tin) w hen dissolved in either of two acids

Cavendish

(spirit of salt and dilute vitriolic acid) give off an
inflammable air. This air, he convinced himself,
came entirely from the metals and not at all from
the acids. He had good reasons for thinking this:
first, the inflammable air was the same whether he
used the one acid or the other, and second, the
same air was generated from different substances,
vegetable and animal. He saw no reason to think
that this inflammable air was anything other than
phlogiston. What is important about this probable
identification for our understanding of Cavendish's
chemistry is that he regarded phlogiston not as a
"principle," as some chemists did, but as a substance
insofar as it had determinable properties like any
other. He collected this substance, inflammable air,
in bottles inverted in water and suspended by
strings, much as Hales had done, and he weighed it
and measured its specific gravity and compared it
with that of water and common air.

Cavendish's first published paper is, in fact,
"three papers," which make them hard to discuss
without introducing confusion; the first paper, on
inflammable air, was read to the Royal Society in
May 1 766, the second and third six months later,
after the summer recess, in November. The three
papers are distinct but related studies. The second
paper, or part two as it is usually called, is about
Black's "fixed air," and it proceeds in the same

"Henry Gucrlac, "Black. Joseph." DSli 2:173-83; "Joseph Black
and Fixed Air. A Bicentenary Retrospective, with Some New or Little
Known Material." Isis4& (1957): 124-51. William Ramsay, The Life and
Utters of Joseph Black, M.I). (London: Constable, 1918), 4-5. 14-15.
'The observation that inspired Black's and his followers' enquiry was
that "chemists have often observ ed, in their distillations, that part of a
body has vanished from their senses, notwithstanding the utmost care-
to retain it; and they have always found, upon further inquiry that
subtle part to be air, which having been imprisoned in the body,
under a solid form, was set free and rendered fluid and elastic by the
fire." Joseph Black. Experiments upon Magnesia Alba, Quicklime, and
Some Other Alkaline Substances, 1756 (Edinburgh, Alembic Club
Reprints. No. 1, 1K9K), quotation on 16.

"The "universal acid." in I ladley, A Plan of a Course of Chemical
Lectures. 5. Discussion of Stahl's "saline principle" in Macqucr,
Dictionary 2:634.

''Water, the "universal menstruum." dissolving all bodies either
immediately or with the aid of acids or alkalis. Neumann. Chemical
Worts, 258.

^Macquer, Elements, 2. From author to author, there were
variations on these principles. Baume's Manuel de chymie, for instance,
was divided into five sections, one for phlogiston as well as one each
for the four elements of the Creek tradition; Baumc says it is
difficult to determine the exact number of elements, p. 16. A. M.
Duncan. " The Functions of Affinity Tables and Lavoisier's List of
Elements," Ambix 17 (1970): 26-42. on 36-37.

5, Cavendish, "Three Papers. Containing Experiments on
Factitious Air." FT 56 ( 1 756): 141 -84; in Sci. Pap. 2: 77-101, on 77.

"'Henry Guerlac, "Joseph Black and Fixed Air." 454-56.

First Researches

PLATE II. Factitious-Air Apparatus. Figure 1 gives Cavendish's technique for filing a bottle I) with air. The bottle is first filled with water and
inverted in the vessel of water K; the air to be captured is generated by dissolving metals in acids and by other means in bottle A. 1 lis measure of
the quantity of air is the weight of the water it displaces in 1). I'igure 2 shows how he transfers air from one bottle to another. Figure 3 shows how
he withdraws air from a bottle by means of a bladder. The speckled substance in Figures 4 and 5 is dry pearl ashes through w hich air is passed to
free it from water and acid. "Three Papers, Containing Experiments on Factitious Air," Philosophical Transactions 56 ( 1 766): 141.

manner as the first; what Cavendish did, in effect,
was to set out and follow the form of a new kind of
study, that of factitious airs. As he did for
inflammable air, he examined the physical properties
of fixed air, and as he did for the quantity of
inflammable air in metals, he determined the
quantity of fixed air in alkaline substances. In this
part, he replaced the water in the collecting trough
by mercury, since fixed air dissolves in water and
not in mercury (as he determined by standing an
inverted flask of it in mercury for "upwards of a
year," which places the beginning of his research
on air at least as far back as 1765). 61 He made the
weights of fixed air in various alkalis meaningful by
expressing their weights relative to the weights of
the alkalis required to saturate an acid; he used as his
standard one thousand grains of the alkali marble.

The point of departure of Cavendish's third
paper, or part three, was the work on fermented
and putrefied substances by David Macbride.
Macbride, five years Cavendish's senior, a phy-
sician in Ireland, published a book of experiments
in 1764 designed to show that fixed air is the
cement of living bodies and that a putrefying body

falls apart because it loses this cement. Macbride
took his understanding of fixed air from Hales, and
he also cited Black, the first to do so in print.'' 2
Cavendish looked to see if fermentation and
putrefaction yielded any factitious airs other than
Black's fixed air. He compared the air from
fermented sugar with that from marble in acid and
found the two to be probably the same, fixed air.
He also obtained air from putrefying gravy broth
and raw meat, which he found to be a mixture of
fixed air and inflammable air, neither pure.

There is a fourth paper in this group, which
Cavendish carefully drafted for publication but then
did not submit. If his third paper was less decisive
than his first two, his fourth paper was even less so.
It again was about vegetable and animal substances,
this time about wood, tartar (his old friend), and
hartshorn (bone) treated by distillation. 63 He obtained

"Cavendish, "Three Papers," 88.

M E. L. Scott, "The 'Macbridean Doctrine' of Air; an
Eighteenth-Century Explanation of Some Biochemical Processes
Including Photosynthesis," Ai/Mx 17 (1970): 43-57. on 44-49.

'■■'This unpublished paper is printed: "Experiments on
f actitious Air. Part IV. Containing Experiments on the Air Produced

Cavendish

a mixture of gases, flammable and nonflammable,
which he could not satisfactorily isolate. 64 He
returned to this subject later, as we know from
his laboratory notes, but with no more success.
I lis unreachable goal was a comprehensive,
systematic treatment of the new field of
pneumatic chemistry, as it would he his goal in
the other major experimental fields he addressed,
electricity and heat.

There was one more paper, an addendum
to his first, and written as if for publication. It was a
fuller version of his discussion of the solution of
metals in acids begun in his arsenic research, and it
was just as tentatively expressed. It begins: "If it is
not digressing too much," and goes on, "I have not
indeed made sufficient experiments to speak quite
positively as to this point." 65 He was not, however,
tentative in his own conviction; at least, there is no
indication he doubted that "no metallic sub-
stance . . . can dissolve in acids without being
depriv ed of its phlogiston" and that the differences
of behavior between different metals in acids are
due to different affinities between the metals, the
acids, and phlogiston. It is clear why he should
have wanted this digression, since his discussion of
inflammable air was incomplete in the first paper.
There he identified this air with phlogiston, which
by his theory is contained in all metals, and so for
completeness, he should have discussed metals
beyond the three of his first paper, zinc, iron, and
tin. In the digression, he discussed experiments
that gave signs of inflammable air, such as
effervescence, but for the most part he had to fall
back on theoretical arguments of affinities to give a
systematic account of the phlogiston of all metals.

In any case, Cavendish's experiments on
factitious air discredited the old notion of a single,
universal air, and in so doing he laid out a new field
of discovery. 'That work alone would entitle
Cavendish to a memorable place in the history of
science, but he was just beginning.

Cavendish has at the same time an impor-
tant place in the history of the British contribution
to science in the eighteenth century. His earlier
chemical researches on arsenic and tartar began
with foreign work, but his work on gases did not. In
connection with gases, he cited seven authors, all
British. Building on what was already a British
tradition, he gave strong direction to the work of
his British colleagues/'''

From his early chemical studies, Cavendish
published one more paper, in the following year,
1767.'' 7 'This, an analysis of a mineral water, did not
have the same significance as his first publication,
but it further demonstrated his chemical skills.
Mineral waters were a prominent subject in chem-
istry, as is evident from John Hadley's Cambridge
lectures, which devote fifteen pages to this
subject.'' 8 Cavendish's second paper was read to the
Royal Society in Tebruary 1767, just three months
after the last part of his first paper on factitious air
was read. 'There was actually an overlap, since in
the unpublished fourth part of his first paper, he
referred to this second paper. His chemical
researches of the 1760s, published and unpub-
lished, were closely connected.

Cavendish's mineral water was not taken
from the shelf, like arsenic. 'The substance occurred
naturally, the water from a London pump, at
Rathbone-IMace. Produced by a spring, the water
until "a few years ago" was raised by an engine for
use by a part of London. Now a pump remained,
from which Cavendish drew his sample, an evil
looking water, "foul to the eye," on which a "scurf
formed upon standing. Cavendish chose this water to
inv estigate for its unwholesomeness, or for a slightly
more technical reason having to do with sediments.

Tump water was studied for practical rea-
sons, for manufactures, drinks, medicine, and above
all health. In the same year as Cavendish's paper,
and probably related to it, a paper on London
pump water was published by his friend William
Heberden as the first paper in the first volume of
the Medical Transactions of the College of Physi-
cians. All of the waters Heberden examined had a
"yellowish cast" and were distasteful and un-
healthy, and yet some Londoners drank them.
1 leberden advised against that practice: Londoners,

from Vegetable and Animal Substances by Distillation." in
Cavendish, Sri. Pap. 2:307-15.

M The mixture, we know, contained marsh gas, carbonic oxide,
and hydrogen. Thorpe, in Cavendish. -Sri. Pup. 2: 315-16.

65 "On the Solution of Metals in Acids. Digression to Paper on
Inflammable Air," in Cavendish, Sri. Pup. 2:305-7, on 305.

"' The authors Cavendish cited arc: Black. Cotes, Hadley, Hales.
Hauksbee, Lewis, and Maebride. Three of these he cited in the
unpublished part 4 and digression. There was one tangential
reference to a foreign work, though no authors were given: the
French publication in 1762 on the measurement of a degree in Peru.

""Experiments on Rathbone-Place Water," PT 57 (1767):
92-108; in Cavendish, Sri. Pup. 2:102-1 1.

*»Coleby, "John Hadley," 300-1.

Copyrighted m aerial

First Researches

155

he said, should not drink the pump waters but the
purer Thames water, which gives us an indication
of the foulness of London water in general. The
best course, Heberden said, was to distill water, for
example, by Hales's method/' 1 ' In the 1760s
London was an unhealthy place, but this was also
the decade in which London began systematically
to improve itself, beginning with the Westminster
Paving Act of 1762. London was described a few
years later:

Beneath the pavements are vast subterraneous
sewers arched over to convey away the waste
water which in other cities is so noisome above
ground, and at a less depth are buried wooden
pipes that supply every house plentifully with
water, conducted by leaden pipes into kitchens or
cellars, three times a week for the trifling expence
of three shillings per quarter. 70

Lead pipes may not sound like an improvement,
but under the circumstances they probably were.
As we would expect, Cavendish's study of pump
water was not motivated by a concern for the
health of Londoners but by a scientific question.
He wanted to know the cause of the suspended
earth, which could not be neutralized by any acid.

The occasion for this research was evidently
a paper in the Philosophical Transactions in 1 765 by
William Brownrigg, a physician in Whitehaven who
studied the foul air from James Lowther's mines.
Brownrigg wanted to know if the coal damps that
caused the miners 's misery were at the same time
similar to the cause of the medicinal virtue of
mineral waters. His paper of 1765 reported that spa
water in Germany released fixed air when it was
heated. 71 Looking to see if the same was true of
Rathbone-Place water. Cavendish arrived at the
answer to his question: the reason for the
suspension of earth in Rathbone-Place water was
its union with more than its normal amount of
fixed air. 72 He concluded his study by looking at
three other London waters, including water from a
pump near his house on Great Marlborough Street.
Cavendish did no more with the subject of mineral
waters, but it was actively developed by other
leading chemists of the time, such as Joseph
Priestley, Torbern Bergman, and Bryan Higgens,
and Cavendish followed their work. 73

Writing about the analysis of waters a few
years later, the Swedish chemist Torbern Bergman
said that it was "one of the most difficult problems

in chemistry" because the quantities were so small
and there were so many impurities in the water. 74
For the same reasons, this was just the kind of
problem to show off Cavendish's skills as a
chemist. But these had already been shown and
acknowledged: for his work the year before on
factitious air, he had been awarded the Copley
Medal of the Royal Society.

That year, 1766, two others shared the
Copley Medal with Cavendish: Brownrigg for his
analysis of mineral water, which we have discussed,
and Edward Delaval for his study of the colors of
metal films. Delaval, who had been Cavendish's
contemporary at Cambridge, was now a fellow of
his college there, Pembroke Hall, and a chemist.
His experiments on thin metal deposits on glass
showed that metals differ in color in the order of
their density: the metal gold and the color red, the
metal lead and the color orange, silver and yellow,
copper and green, and iron and blue. Delaval
regarded his work as an extension of Newton's on the
relation of the dimensions of thin plates to the colors
they produce. 75 His paper was a paper on chemical
optics. The year 1766 was the year of the chemists.

Before we leave this discussion of Cavendish's first
publications, we want to say something more about
one of his sources, William Brownrigg. We have
pointed out Brownrigg 's connection with Sir James
Lowther, an active member of the Royal Society
and a relative of Lord Charles and Henry

'•''William Heberden, "Remarks on the Pump-Water of London,
and on the Methods of Procuring the Purest Water." Medical
Transai /ions 1 (1767): 1-22, on 2. 19.

7I, M. Dorothy George, London Life in the Eighteenth Century
(Harmondsworth: Penguin Books, 1966), 110-11.

7l William Brownrigg, "An Experimental Enquiry into the
Mineral Elastic Spirit, or Air, Contained in Spa Water; as Well as into
the Mephitie Qualities of this Spirit." FT 55 (1765): 218-35.
J. Russell-Wood, "The Scientific Work of William Brownrigg, M.I).,
KR.S. (171 1-1800). — I," Annals of Science 6 (1950): 436-47, on
436-58,441.

"Cavendish, "Experiments on Rathebone-Place Water," 107.

"Cavendish's papers contain a table comparing the analyses of
seltzer, spa, and Pyrmont waters by Bergman and 1 Iiggcns. Cavendish
Mss, Misc. This table would have been prepared after Bergman's
analyses of mineral waters in the 1770s, probably after 1778.

74 Torbern Bergman, "Of the Analysis of Waters," in his Physical
anil Chemical Essays, trans, with notes by Kdmund Cullen, vol. 1
(London, 1784), 91-192, on 109.

"Edward Delaval, "A Letter . . . Containing Experiments and
Observations on the Agreement between the Specific Cravitics of
the Several Metals, and Their Colours When United to Class, as
Well as Those of Their Other Preparations," W55 (1765): 10-38.

156

Cavendish

Cavendish. In 1741 Lowther communicated a
paper by Brownrigg to the Royal Society, entitled
"Some Observations upon the Several Damps in
the Coal Mines Near Whitehaven." Since that
paper is found among I lenry Cav endish's scientific
manuscripts at Chatsworth, the suggestion is that
Cavendish knew of this early work on air by
Brownrigg and took an interest in it. British
fascination with air had its origins in part in the
violence of its mining industry. Brownrigg studied
the two kinds of coal damps, the fire damp which
catches fire explosively, and the choke damp which
puts out fire (and life). If the fire damp is ignited
deep inside a mine, "the Consequence is the most
dreadful imaginable," with "an explosion equal to
that of Ounpowder," killing "every living thing"
near and far. After the explosion, the fire damp
becomes choke damp, "a deadly Poison." 7 ' 1
Brownrigg referred to I lalcs's recent experiments
on elastic air, and in the next year, 1742, Hales
addressed the same problem in the Royal Society,
the foul air inside mines. 77 A sequel by Brownrigg
to his paper on "mineral exhalations" was again
presented by Lowther and read at sev eral meetings
in early 1742, and in it he addressed "Mineral
Waters" as well. 78 This paper concluded with a
discussion of the usefulness of a knowledge of
mineral exhalations for "discovering the nature and
properties of common Air." 7 '' Common air was the
principal subject of interest to Henry Cavendish
throughout his work in the chemistry of "airs."
Through Lowther, a family connection may have
become a scientific connection for Cavendish.
Brownrigg s work was, in any case, a direct stimulus
for Cavendish's work on mineral waters and
perhaps too on the chemistry of air.

Heat

At about the same time that Cavendish
performed his first dated chemical experiments, he
began a series of experiments on specific and latent
heats, which he recorded in an untitled, unindexed
packet of 117 numbered small sheets. 80 The
experiments are rarely dated; the first and earliest
date, 5 February 1 765, occurs only near the end of
the record. But the few dates given are in order,
and the sequence of experiments follows a natural
progression of questions and answers. These
sheets, in fact, make compelling reading, con-
veying the feel of experimental research leading to

important and unanticipated results. Although
Cavendish did sometimes reorder the notes of his
experiments for his own reference, the interruption
of chronology is generally slight and obvious; for
example, occasionally in a group of heat experi-
ments, the "3rd exp." will be followed by the "1st
exp." These sheets were not the original slips
containing the measurements taken in the
laboratory but an intermediate record, from which
Cavendish later wrote a proper paper. Although
this paper is still in rough draft, it is carefully
worked out; Cavendish wrote it with an
unidentified, specific reader in mind, "you." 81 This
person too could have been John Hadley. 8 -'

Whereas we can speak with some con-
fidence of what inspired Cavendish's earliest
chemical experiments, the origin of his heat
experiments is less clear to us. In a broad sense,
however, these experiments are readily intelligible.
Cavendish's father took great interest in ther-
mometry, and others at the same time were working
on the same subject. Then there is a matter of
timing: just as Cavendish came forward as a
scientist, in the 1760s, the experimental field of heat
emerged as a quantitative science. Central to this
development was the clear distinction between, and
the relationship between, thermometer readings and
quantities of heat. The quantitative concepts of
specific and latent heats were the particular subject
of Cavendish's researches. Although the immediate
inspiration for Cavendish's heat experiments is
probably unknowable, a reasonable speculation can
be made about it.

Apart from Cavendish's own, the most
important researches on heat and chemistry in
Britain were not made in London. What Cav endish
knew of them he learned from publications or by

"Knyal Society. JB 1 7:239-43 (16 Apr. 1 741 ).

77 Royal Society, JB 17:403 (6 May 1742). Brownrigg's paper
prompted Males and Sloane to urge him to write a history of coal
damps, which he did hut did not publish.

"Royal Society. JB 1 7:394 (8 Apr. 1 742 ).

'•'Royal Society. J B 17:405 (13 May 1742).

""Henry Cavendish Mss 111(a). untitled bundle.

"'Henry Cavendish, "Experiments on Heat." Set. Pap. 2:327-47.
Cavendish's experiments on heat are described in Vernon Hareourt,
"Address," British Association Report, 1839, pp. 3-68, on pp. 45-50;
and in Wilson, Cavendish, 446-54. Both of these commentators art-
concerned mainly with claims of priority in the discovery of specific
and latent heats.

"-'In his chemical lectures. Hadley talked about heat, and it
would seem that he held, as Cavendish did. the motion theory of
heat. Coieby, "John Hadley." 298.

Copy rig hied m aerial

First Researches

151

hearsay. Cavendish mentioned only one name in
his experimental notes, "Martin." This reference
comes at the end of the packet and probably has
nothing to do with the origin of Cavendish's
researches on heat.* 3 He clearly meant the Scottish
physician George Martine, who in 1740 published
an account of rates of heating and cooling. In the
approximately fair copy of his experiments, he
mentioned three names, all in connection with
latent heat. One reference was to the French
physical scientist Jean Jacques Mairan and the
production of heat by the freezing of water, but
Mairan's work came twenty-five years earlier. 84
The other two references were to the Scottish
chemists Cullcn and Black.

(aiilen, the older of the two, was professor
of medicine and lecturer in chemistry at the
University of Glasgow, in whose laboratory Black
worked for a time, and whom Black succeeded
later as lecturer in chemistry. Cullen moved to the
University of Edinburgh as professor of chemistry
in 1756, in which position Black again succeeded
him ten years later. In 1755 Cullen published an
account of the cooling produced by evaporation,
which originated in the simple observation by a
student that a thermometer cools when it is
removed from a solution. Cullen recalled a similar
observation by Mairan, and he suspected that
evaporation was the cause and made experiments
to find out. He evaporated some thirteen liquids,
acidic and alkaline, producing cold of "so great a
degree" that he thought it had not been observed
before, and for this reason he thought this whole
subject should be "further examined by
experiments."* 5 If not from the beginning, by the
time Cavendish wrote up his heat experiments, he
knew of this work by Cullen and thought well of
it. 86 Going much farther than Cullen, Black made a
thorough investigation of specific and latent heats,
the first to do so. 87 Black published nothing of this
work, but he did include it in his lectures. 88 In
1760, originally prompted by Cullen's experiments
on the cold produced by evaporation, Black began
his experiments on heat. 8 '' He realized that the
commonly held opinion that bodies exchange heat
in proportion to their mass was wrong: different
kinds of matter communicate heat differently, "for
which no general principle or reason" had been
given. Black s own reason, based on the concept of
specific heat, came to him after reading Martine's

essay on rates of heating and cooling and Hermann
Boerhaave's Elements Chemiae^ As it happened he
came upon the idea of latent heats before that of
specific heats, and his clue once again came from
Boerhaave's text. Perhaps as early as 1758, before
he had done any experiments, he lectured on the
heat involved in changes of state of substances. To
convey this concept, he gave this homely and
effective example: if snow and ice were to melt
immediately at the melting temperature, the
commonly held view, then every spring the world
would suddenly be overwhelmed by floods, which
"would tear up and sweep away every thing, and
that so suddenly, that mankind should have great
difficulty to escape from their ravages." The reason
why this did not happen is that it takes a long time
for ice and snow to absorb the heat that originally is
lost in the change of state of water to ice and snow.
Black did experiments to confirm and quantify the
"latent heat" — his term — of the liquefaction and
solidification of water.'" None of this information
reveals when and what Cavendish knew of Blacks
work. 1 ' 2 Both Cullen and Black were great teachers,
and Black was a great investigator too, but neither
published much research, even compared with the

"Cavendish Mss 111(a), 9:114. His reference is probably in George
Martine's Essays Medical find Philosophical, published in London in
174(). S4 I lenrv Cavendish. "Kxperiments to Show That Bodies in
Changing from a Solid State . . .," AW. Pap. 2:348. His source was
probably J. J. d'Ortous de Mairan's Dissertation sur la glace, mi
Explication physique de la formation de la glace, c? divers phenomenes
(Paris, 1749).

85 Cullcn's paper was first published in 1755 in the Edinburgh
Philosophical and Literary Essays and was republished together with
Black's essay. Experiments upon Magnesia All/a. Quiet-lime, and Other
Alkaline Substances; by Joseph Mack. To Which Is Annexed. An Essay on
the Cold Produced by Evaporating Fluids, and of Some Other Means of
Producing Cold; by William Cullen (Edinburgh. 1777). 115-33,
quotation on 132.

""■Cavendish wrote: "Or. Cullen has sufficiently proved that
most if not all fluids generate cold by the first species of
evaporation." By "first species," Cavendish meant evaporation by
heating a liquid but not boiling it, in which case the evaporation was
due to absorption by the air. Cavendish, "Experiments on I leat," AW.
Pap. 2: 344.

" 7 The Swedish physicist Johan ( !arl Wilcke discovered latent heat
independently of Black and later, in 1772, but unlike Black he
published his finding. His work on latent and specific heats is discussed
in detail in Douglas McKie and Niels II. de V. Heathcote, The
Discovery of Specific and Latent Heats (London: Arnold, 1935), 54-121.

""Black's Lectures on the Elements of Chemistry, edited by his pupil
John Robison. and published in two volumes in Edinburgh in 1803.

"Guerlac "Black." 177.

'"'Quotation from Black's Lectures in McKie and Heathcote.
Discovery, 13.

'"Ibid., 16-20, quotation on 16.

"^Douglas McKie, "On Thos. Cochrane's MS. Notes of Black's.
Chemical Lectures, 1767-8," Annals of Science I (1936): 101-10, on 103.

158

reserved Cavendish. When Cavendish wrote in his
paper on heat that he was "informed" that Black
had made observations on the heating of a worm
tube by condensing water, he meant informed by
word of mouth, and that could have happened
anywhere at any time. As a regular attender of the
meetings of the Royal Society and of the dinners of
its club, ( lavendish was well placed to learn of Black's
work. We think that it was probably from his friend
John Hadley that Cavendish heard about Cullen's
work and with it Black's. Our evidence is a letter
Benjamin Franklin wrote in 1762 in which he
described the repetition of one of Cullen's experi-
ments by John Hadley: "Dr. Cullen of Edinburgh,
has given some experiments of cooling by evapo-
ration; and I was present at one made by Dr.
Hadley, then professor of chemistry at Cambridge,
when, by repeatedly wetting the ball of a ther-
mometer with spirit, and quickening the evapo-
ration by the blast of a bellows, the mercury fell
from 65, the state of warmth in the common air, to
7, which is 22 degrees below freezing.'"" This was
one way that heat experiments in Scotland were
learned of in London, and it was probably
Cavendish's way, and for him the timing would
have been just about right.

Cavendish knew about Black's work while
he was still engaged in his own; this we know,
because he said so. He had heard about Black's
experiment on water in the worm tube of a still,
but he did not know how the experiment came
out, which is why he repeated it; by then
Cavendish and Black were doing parallel
researches on heat. It is likely that Cavendish came
to his experiments on heat not directly through
Black but by more or less the same route that Black
took. Cavendish wrote of his findings on specific
and latent heats as discoveries, as the theoretically
unexpected; his laboratory notes on latent heat
reinforce the impression of surprise. Boerhaave's
text on chemistry, which guided Black, and which
was recommended reading at Cambridge when
Cavendish was there,'' 4 reported on Daniel Gabriel
Fahrenheit's experiments on the hardening and
melting of a substance, which showed that change
of state involves a heat that does not register on the
thermometer. Black called this heat "latent heat."
Boerhaave also reported on Fahrenheit's
comparison of the heating effects of mercury and
water: mercury and water, Fahrenheit found, have

Cavendish

different heat capacities, or specific heats. 45
(Fahrenheit was an instrument-maker, a friend of
Boerhaave, and a Fellow of the Royal Society, who
published papers on meteorological instruments in
the Philosophical Transactions. His most famous
achievement was his thermometer scale, which was
adopted in Britain.) Black began his own experi-
ments on heat with an examination of the reliability
of the thermometer as a measuring instrument. 96
(Like Cavendish, he did not think it was reliable,
as he said in his lectures at about this time: "These
/thermometers/ are very usefull in difft. Fxpts. but
very fallacious seldom agreeing for they are liable
to some variations.'"' 7 ) That concern with
thermometers, we think, is the probable origin of
Cavendish's experiments too. In addition to
Fahrenheit and Boerhaave, Brook Taylor may be
considered a source of Cavendish's work in this
connection. In the Philosophical Transactions in
1721, Taylor published a study of thermometers, in
the course of which he mixed given quantities of
hot and cold water and measured the original and
res u 1 1 i ng te m pe ra t u res. l ' K

The instruments Cavendish needed for his
heat experiments were few: lamps for heating
mixtures in bottles made of glass or tin, ther-
mometers, scales, and a watch. His method was
that of mixtures, and he began his experiments
with the simplest of mixtures, Fahrenheit's hot and
cold water. He took three readings three minutes
apart to determine the rate of cooling of the hot
water and the warm mixture, and he did a separate
experiment to determine the heating effect of the
container. He found, as he expected, the "true
heat" of the mixture to be the weighted mean of

,3 Benjamin Franklin to Kbcnczer Kinnersley, 20 Feb. 1762, in
Benjamin Franklin. Benjamin Franklin's Experiments. A New Edition of
Franklin's Experiments and Observations on Electricity, ed. I. B. Cohen
(Cambridge, Mass.: Harvard University Press, 1941), 559-75, on 360.
Franklin was in London in 1762, as the agent () f the Pennsylvania
Assembly.

''■'Boerhaave's A New Method of Chemistry is listed in Christopher
Wordsworth. Srholae Academicar: Some Account of the Studies at the
English Universities in the Eighteenth Century (Cambridge. 1877), 79.

"Gucrlac, "Blaek." 177-78.

'"'Ibid.. 177.

" 'Notes from Doctor Black's I Mures on Chemistry 1767/8, ed. I).
McKie (Cheshire: Imperial Chemieal Industries. 1966), 8.

'"Taylor's experiments were reported in the Philosophical
Transactions for 1721: they are deseribed in A. Wolf. .1 History of
Science, Technology, c? Philosophy in the IHlh Century. 2d ed. by
D. MeKie. 2 vols. (New York: Harper & Bros.. 1961) 1:189-90.
Wilson, Cavendish, 447.

First Researches

159

the temperatures of the hot and cold water before
mixing: "It seems reasonable to suppose that on
mixing hot and cold water the quantity of heat in
the liquors taken together should be the same after
the mixing as before; or that the hot water should
communicate as much heat to the cold water as it
lost itself." iw Then, using the same procedure, but
varying the apparatus somewhat, he mixed
alternately hot water, mercury, and spirits with cold
mercury, spirits, and any of a number of substances.
These substances he took, in part, from his shelves
of chemical reagants, oil of vitriol and solution of
pearl ashes. Cavendish's heat and chemical re-
searches crossed paths here in ways that would, as
wc will sec, affect his fundamental theory of matter
and motion. 100 The substances also included solids,
such as sand, iron filings, shot, powdered glass, marble,
charcoal, and brimstone, and other solids broken
into lumps smaller than peas: tin, Newcastle coal,
and spermaceti. He expressed his anticipated
conclusion upon mixing different substances this
way: "One would naturally imagine that if cold
/mercury/ or any other substance is added to hot
water the heat of the mixture would be the same as
if an equal quantity of water of the same degree of
heat had been added; or, in other words, that all
bodies heat and cool each other when mixed
together equally in proportion to their weights. The
following experiment, however, will show that this
is very far from being the case." 101 The "true explana-
tion" is that "it requires a greater quantity of heat
to raise the heat of some bodies a given number of
degrees by the thermometer than it does to raise
other bodies the same number of degrees." 102
Cavendish used water as the standard for calculating
the "equivalent" weight of each substance in terms
of its heating effect; he determined, that is, the
specific heat of each substance. His experiments
on specific heats proceeded smoothly until he came
to spermiceti, whereupon he stopped to do a long
series of experiments on this substance alone. 103
The minutes of the experiments suggest that
spermiceti was a mess to handle and to measure. If
the reported sequence of experiments corresponds
roughly to the actual sequence, the minutes
suggest that spermaceti was also the source of a
major discovery, that of latent heats. In the first of
the spermiceti experiments, Cavendish mixed cold
lumps with hot water, in the next hot melted
spermiceti with cold water, and he found that the

results disagreed. The only difference in the two
trials was the condition of the spermaceti, solid in
one trial, liquid in the other. That was Cavendish's
clue; he concluded that when spermiceti hardens it
gives off heat and when it melts it produces cold,
and that this heat is characteristic of spermaceti.
That is, there is a second heat in addition to the
specific heat of a substance. 104 The next experiment
was with a more tractable substance, water, for
which Cavendish built a new apparatus. With it he
measured the cold produced by boiling water; that
is, by changing its state from liquid to vapor. 105 The
conclusion he drew about latent heats was this: "As
far as I can perceive it seems a constant rule in
nature that all bodies in changing from a solid state
to a fluid state or from a non-elastic state to the state
of an elastic fluid generate cold, and by the contrary
change they generate heat." 10 ' 1 Then, evidently to
achieve more accuracy, he began all over again with
the simplest mixture, hot and cold water, but now
with a new apparatus, a funnel into which the hot
water was poured and which was tightly joined to a pan
containing the cold water; stirrers and thermometers
were inserted in both the funnel and the pan. The
measured heat of the mixture and the theoretically
computed heat now agreed to within a half degree,
a realistic accuracy for experiments of this kind. 107
It has been suggested that Cavendish did

"Cavendish, "Experiments on Heat," 327.

'"" The chemical mixtures generated an additional heat or cold,
w hich Cavendish noted in these small sheets. He would later give an
explanation for these heats in terms of a change in specific heats
resulting from the reaction.

""Cavendish, "Experiments on Heat," 332.

'"^Ibid., 340.

'"'Cavendish Mss IIKa), 9:22, 27-38.

l04 The heading of his experimental notes on p. 31. Cavendish
Mss IIKa), tells of this discovery: "Concerning I leat cx Cold Produced
by Hardening & Melting of Spermaceti." Cavendish measured the
latent heat of spermaceti several times, obtaining only roughly con-
sistent results; he found that the hardening of spermaceti was sufficient
to raise an equal weight of water by about 64 to 75 degrees; the cold
generated by the melting of it fell in that range, about 69 degrees.
Cavendish returned to spermaceti using a different experimental
arrangement and got higher values. Ibid., 78-K1. I lis experiments on the
change of state of water betw een solid, liquid, and vapor gave much
more consistent results, and these he emphasized in his intended paper.
He only just briefly mentioned there that he had found the same kind
of phenomenon w ith hardening and melting spermaceti. This section
Cavendish headed "Experiments to Show That Bodies in Changing
from a Solid State to a Fluid State Produce ( lold and in Changing from
a Fluid to a Solid State Produce Heat." AW. Pap. 2:348-50, on 349.

l0, Cavendish Mss IIKa), 9:42— M . This experiment Cavendish
wrote up in his paper "Experiments on Heat." and the apparatus is
drawn there. AW. Pap. 2:345-46.

l06 Cavendish, "Experiments on Heat," 343.

" l7 Cavendish Mss IIKa), 9:48-56. This apparatus, which Cavendish

160

Cavendish

not publish his experiments on heat beeause he-
did not want to enter into rivalry with Black in a
field that Black had staked out tor himself. 10 * That
may be correct, but it seems unlikely. There is
rarely any worthwhile work in science that does not
bring its author into rivalry, and in his first
publication, on factitious air, Cavendish was not
deterred by Black's prior work on fixed air; Black
had even staked out a claim by saying that he
intended to do more work on the subject. The onlv
difference was that Black published his original
experiments on fixed air and he did not his
experiments on heat. We think that Cavendish
refrained from publishing for a reason of a different
kind: his experiments raised difficult problems for
his theory of heat. Cavendish tried to resolve the
theoretical problems, at first without success, and
by the time he did succeed there was no point in
publishing. Black's lectures were, in effect, a slow
but sure publication; before 1780, a number of
researchers in Britain were working with the
concepts of heat that Black had communicated
through his lectures. There also appeared work
from abroad such as Johan Carl Wilcke's.

Cavendish did publish on heat, but it was not until
1783, when he invoked the rule of latent heat in a
discussion of the freezing of water, and he gave
neither an argument nor a citation for it but simply
remarked that it was a "circumstance now pretty
well known to philosophers." W) Even though
Cavendish did not publish his experiments on heat,
his effort was not wasted. He had acquired a thorough
familiarity with the phenomena of heat, which
would serve him well in his researches over the
next twenty years.

described and drew in his paper "Experiments on I Icat," is reproduced
in Sci. Pap. 2:.?2K. Cavendish's readings and calculations were onlv as
accurate as the experiments allowed. He kept minutes by a watch, read
degrees of" heat no finer than 'A degree, and when estimating rates of
cooling, he used comparably rough calculations, such as (2 + YA)l?i = 1.
I Ic repeated his experiments and took a mean of the readings, and if the
mean should be. say, 90.1, in the paper he would round it off to 90.

'""Wilson. Cavendish, 446. McKie and I Icathcotc agree with
Wilson, in Discovery, 52.

""This "circumstance'' is "that all, or almost all. bodies by
changing from a fluid to a solid state, or from the state of an elastic to
that of an inelastic fluid, generate heat: and that cold is produced by
the contrary process." Henry Cavendish. "Observations on
Mr. Hutchins's Experiments for Determining the Degree of Cold at
Which Quicksilver Freezes," FT 73 (1783): 303-28; in Set. Pap.
2:145-60, on 150.

Copyrighted m aerial

CHAPTER 4

Tools of the Trade

Instruments

Instruments, mathematics, and theory are
principal tools of science, and like every good
craftsman, Cavendish kept his tools sharp, giving at
least as much attention to them in their own right
as to their use in experiments with other ends. We
begin this discussion with the instruments of
science: Cavendish regularly compared his instru-
ments, one with the other, and one after another,
thermometer, barometer, hydrometer, electrometer,
clock, compass, telescope, and eudiometer. His
interest and skill were recognized by the Royal
Society, which regarded him as its resident authority
on all matters having to do with instruments.

Henry Cavendish varied and perfected
existing instruments instead of inventing new
ones. Beginning with his father's self-registering
maximum and minimum liquid thermometers, the
first of their kind, Henry Cavendish designed a
convenient, self-registering, dial-type maximum
and minimum thermometer, an all-in-one instru-
ment. In it a mechanism registers a change in the
height of mercury by a rotary movement of an axis;
the instantaneous temperature is read by a large
pointer, and the maximum and minimum tem-
peratures are recorded by light pointers moved by
the large one. 1 To take another example: like many
meteorologists before and after him, Cavendish
designed a better wind measurer. Having com-
missioned the firm of Nairne and Blunt to build it
for him, Cavendish requested to meet with the
employee who made the instrument on the
premises, whereupon Cavendish "insisted upon his
taking the whole apparatus to pieces, and then, by
means of a file and a magnifying glass, he tested
the pinions to see that they were properly
hardened and polished, and of the right shape,
according to his written directions." 2 We suppose
that during this inspection of the pinions, the
instrument-maker felt some anxiety, but since the
anecdote ends here, we also suppose that the

outcome was favorable to all parties. At Nairne and
Blunt, Cavendish was both a demanding customer
and a frequent one, whose behavior, if tactless,
would have been familiar and more than tolerated,
since his patronage of the firm was an
advertisement of a kind that money could not buy.
The founder of the firm, Kdward Nairne, a Fellow
of the Royal Society, was Cavendish's all-purpose
instrument-maker of choice and also an experi-
mental collaborator of his.'

In the 1760s and 1770s, at about the time
Cavendish began to do research, the experimental sci-
ences were beginning to be supplied with instru-
ments for making exact measurements. Aided by
improvements in mechanics, in materials such as
brass, steel, and glass, and in the graduation of scales,
the makers of scientific instruments responded to
the expanding demand for accurate instruments,
and their product in turn stimulated the demand
for ever greater accuracy. 4 Living in the same city
with the instrument-makers, Cavendish could con-
veniently inspect, buy, and commission their wares.

'This instrument was calibrated at Chatsworth in 1774. which
more or less dates it. Lord Charles Cavendish could have designed it,
but at that late date the designer was more likely Henry Cavendish.
The self-registering thermometer is one of two instruments (the
other a metallic eudiometer) illustrated anil described in an appendix
in George Wilson, The Life of the Honourable Henry Cavendish (London,
I S5 1 ). 477-78. Through Humphry Davy, this instrument was eventually
given to the Royal Institution. William E. knowlcs Middleton, A
History of the Thermometer and Its Use in Meteorology (Baltimore: The
Johns Hopkins University Press, 1966), 138-39. Related to this
thermometer are undated experiments by Henry Cavendish,
"Thermom. for Crcatest Heat by Inverting the Knd of Tube into a
Moveable Cyl. of Spt. & Water," Cavendish Mss 111(a), 14(e).

2 This anecdote about Cavendish originated with the
instrument-maker John Newman, of Regent Street. Wilson.
Cavendish, 1 79.

'Discussion of and entries for Kdward Nairne and Thomas
Blunt in E. G. R. Taylor, '////■ Mathematical Practitioners of Hanoverian
England, 1714-1840 (Cambridge: Cambridge University Press, 1966),
62.214. 256.

J \Iauricc Daumas, "Precision of Measurement and Physical and
Chemical Research in the Eighteenth Century." in A. C. Crombie,
ed.. Scientific Change; Historical Studies in the Intellectual, Social, and
'Technical Conditions (or Scientific Discovery and 'Technical Invention, from
Antiquity to the Present (New York: Basic Books. 1963), 418-30. on
418, 426-30.

162

Cavendish

At some point his need for the services of
instrument-makers became so constant that he
employed one of his ow n.

Because he was wealthy, Cavendish could
own any instrument he wanted, and because his
scientific interests were wide-ranging, he owned a
large number of instruments. In 1816, six years
after his death, his collection was put up for sale.
The catalogue of the auction 5 lists 91 numbered
items, some of which arc multiple; all told, it
mentions about ISO instruments together with
bottles, retorts, and maps, the lot selling for 159
pounds. The unnamed buyers of the instruments
were probably persons who had use for them, since
instruments used by Cavendish in the 1780s were
still in use at the time of the sale, and Cavendish
was not yet famous enough for his instruments to
be collected as memorabilia; his name was not
mentioned in the catalogue, only a "Ccntleman
Deceased." In some instances, an instrument is
listed with the maker's name as a guarantee of
quality; e.g., an air pump and a dipping needle by
Nairne and Blunt, a thermometer by John Bird,
and a theodolite and a thermometer by Jesse
Ramsden. By the time of the auction, Cavendish's
collection of instruments and related apparatus had
been scavenged, stripped of all of its electrical
measuring instruments and nearly all of the
instruments for measuring gases, leaving mainly
drawing instruments, telescopes, variation compasses,
hygrometers, and thermometers (44 of them). 6 As
we will see, the balance — or imbalance — of the
collection is not too misleading; Cavendish
devoted much of his life to the study of instruments
of the earth's atmosphere and magnetism.

The probable reason why Cavendish
commissioned the firm of Nairne and Blunt to
build his wind-measurer was, apart from habit, the
portable wind gauge for use at sea that Nairne and
Blunt had recently built for James Lind, physician
to George III. 7 It was the best instrument of its
kind, which was the kind of nearly all early wind
gauges. They were, in effect, pressure gauges,
designed for "weighing the wind," used by
seamen, who were interested in that property of
the wind, its pressure/ Cavendish's wind measurer
was of a different kind, one suited for meteorology,
in the tradition of the vane-mill invented by
Robert I looke in the previous century. 9 The
inspirer of Cavendish's earliest experiments would

have been Alexander Brice, who measured the
velocity of the wind by observing the motion of the
shadows of clouds, his answer to the irregularities
in the velocity of wind as determined by light
objects like feathers carried along in the breeze.
Presumably the wind is unobstructed at the height
of clouds. 10 Cavendish thought that Brice's experi-
ments published in the Philosophical Transactions in
1766 were "ingenious" but incomplete, since Brice
failed to measure the wind on the ground in an
open place to discover if there is a difference in
wind velocity at the surface of the earth and high
above it, and Brice also failed to observe the
angular velocity of the clouds at the same time as
he observed their shadows, which would have
determined their perpendicular altitude. "The
most convenient way I know of measuring the
velocity of the wind," Cavendish wrote to a
correspondent, "is by a kind of horizontal windmill
with rackwork like that used for measuring wheels
to count the number of revolutions it makes. Such
an instrument will make the same number of
revolutions while the wind moves over a given
space whether the wind moves fast or slow & it will
be easy finding by experiment the actual number
of revolutions which it makes while the wind
moves over a given space."' 1 Cavendish's apparatus
in the 1760s was such a horizontal windmill and
built nearly on the scale of a true windmill, the
revolving arm measuring about eighteen feet long.
Twenty years later, no doubt with the Nairne and
Blunt instrument this time, he returned to these

5 Wc arc fortunate to have the catalogue of Cavendish's
instruments, since few instrument catalogues from the eighteenth
century have been preserved. Another surviving catalogue is that of
John Stuart, carl of Bute, who had a large instrument collection
rivaling that of his friend George III. The catalogue of its auction sale,
listing 2.S.S numbered items, has a large overlap with the catalogue of
Cavendish's collection, especially in the category of "mathematical."
or drawing, instruments, G. I,'K. Turner. "The Auction Sales of the
Karl of Bute's Instruments, 1793," Annals of Science 23 (1967): 213-42.

b A Catalogue of Sundry Very Curious and I 'editable . Mathematical,
Philosophical, and Optical Instruments, Electrifying Machines, Clocks, and
Maps of a Gentleman, Deceased . . . Whith Will lie Sold Ay Auction, fry Mr.
Wi/loci, on the Premises. So. Jl . in Sherrard-Slreet. Above-Mentioned, on
Saturday the Fifteenth of June 1816, at Twelve O'clock. Devon. Coll.

"Taylor, Mathematical Practitioners, 62-63.

K A. Wolf, A History of Science, '/ethnology, of Philosophy in the 18th
Century. 2d ed.. ed. I). McKic. 2 vols. (New York: Harper & Bros.,
1961) 1:320-23.

''William E. Knowles Middleton, Intention of the Meteorological
Instruments (Baltimore: Johns 1 lopkins 1 niversitv Press, 1969), 203.
"'Wolf, History of Science. 324.

"Henry Cavendish to "your Lordship," undated. Cavendish
Mss, Misc.

Tools of the Trade

163

experiments. Sinee his method was to count the
number of revolutions corresponding to winds of
different strengths, 12 the accuracy of the pinions
that he insisted on testing on Nairne and Blunts
premises was the key to the accuracy of the
instrument across a wide range of wind velocities.

To his correspondent Cavendish revealed
his hope for the wind measurer: "By the help of
such an instrument one might easily find the
velocity of the wind at any time & if one had a
mind keep a register of its velocity almost as easily
as one can that of the thermometer." 13 Ideally,
then, a complete weather journal would record the
velocity of the wind in addition to its direction,
which was then routinely observed by the weather
vane. If that indeed was Cavendish's wish, it was
not to be realized; complex and cumbersome wind
measurers were invented and reinvented throughout
the century, without leading to a standard practice.
By the procedures recommended by Cavendish for
recording the weather at the Royal Society, the
strength of the wind was denoted numerically, but
only conventionally: 1, 2, and 3 stood for "gentle,"
"brisk," and "violent or stormy." 14 The clerk was
advised to look at how smoke was blown or how
the wind sounded, 15 which was a far cry from
reading the revolutions of a wind measurer. Like-
many other patient observers of the weather,
Cavendish desired exactness and had to settle for
less. There had long been instruments for the
weather, the weather vane, the rain catch, and even
a crude indicator of humidity, but these did not make
the study of the weather exact. By Cavendish's
time, it was understood that the science of the
weather required instruments to measure it; above
all, the thermometer and the barometer. 10 At the
same time it was understood that these instruments
were still primitive. The difference in rigor between
an exact science and meteorology at the beginning
of the eighteenth century can be appreciated by
Newton's experiments on thermometry. The
author of the system of the world used a linseed-oil
thermometer and a scale fixed by two points, the
heat of the air standing above water when it begins
to freeze, and the heat of blood, from which
Newton extrapolated freely to high temperatures. 17
Nearly forty years later, Robert Smith, who translated
Newton's directions for making thermometers,
observed that none of the thermometers he had
seen had been tested for comparability, 1 * which

was still pretty much the state of affairs when
Cavendish took up the study of thermometers
thirty years later. 14 There was a variety of scales in
use and a wide variation in their adjustment;
Britain and Scandinavia preferred the Fahrenheit
scale while the nations on the Continent preferred
the Reaumur scale.- 0 When Cavendish received his
first assignment from the Royal Society, to measure
the boiling point of water, in 1766, thermometers
were just then beginning to be calibrated for
improved accuracy. 21 The boiling point of water
was a problem basic to thermometry, and
Cavendish's object was to determine if the boiling
point is affected by the rapidity of boiling and by
the thermometer's immersion either in the boiling
water or in the steam above the water. The
potential accuracy of a thermometer — the fractions
of a degree to which it could be read — had little
meaning in practice, since the results of different
thermometers and of different users were wildly
discordant, owing especially to an uncertainty
regarding the upper point of the scale, the boiling
point of water. Of the selection of excellent
thermometers, built by Bird, Ramsden, Nairne,
and Ceorge Adams, tried by Cavendish (probably
with other Fellows) at the Royal Society in 1766,
individual thermometers differed in their readings
of the boiling point by two or three degrees. 22
While astronomical precision in meteorology was not
regarded as important or obtainable, 23 a disparity of
two or three degrees in the boiling point of water on

12 Henry Cavendish, " No. 1. Measurer of Wind," Cavendish
Mss, Mist. Dates arc scattered through the trials: the spring of 1768
and of 1769, and twenty years later, in the fall of 1788. " Trial of
Windgage."

"Cavendish, letter to "your Lordship."

l4 Henry Cavendish, "An Account of the Meteorological
Instruments Used at the Royal Society's House," PT 66 (1776):
375-101; in Set. Pap. 2:1 12-26, on 1 1 7.

"Royal Society, Minutes of Council 6:202 (9 Dec. 177.3).

"' Typical on this point is Richard Kirvvan, An Estimate of the
temperature of Different Latitudes (London, 1787), iii.

l7 Middlcton, History of the Thermometer, 57-58.

'"Robert Smith, "The Kditor's Preface," in Roger Cotes,
Hydrostatical and Pneumatical Lectures, 2d ed. (Cambridge. 1747).

''' There was, as we have noted, a general understanding that
mercury was the best substance for a thermometer, though that did
not diminish interest in thermometers using other substances: Henry
Cavendish, "Thermometers of Different fluids," Cavendish Mss
111(a), 14.

'Middlcton. History of the Thermometer, 65, 75, 1 15.

J 'Middleton dates the increase in accurate calibration from
about 1770: History of the Thermometer, 127.

--Henry Cavendish, "Boiling Point of Water. At the Royal
Society, April 18, 1766," in Cavendish, Set. Pup. 2:351-55.

-''Middlcton. History of the Barometer, 132.

164

Cavendish

different thermometers was, to Cavendish's way of
thinking, unacceptable and correctable. Instrument-
makers might stress the accuracy attainable with a
given instrument; Benjamin Martin, for example,
claimed that with a vernier the barometer could be
read to l/l()()th of an inch (in a column of mercury
of 28 inches),- 4 and from the 1770s verniers and
indices were used for reading the level of mercury
in the barometer tube (on the mercury tubes of
thermometers, verniers were not useful). 2 " but
Cavendish was not primarily concerned with
accuracy in that sense; he was concerned with the
consistency and compatibility of readings with
instruments used by different observers.

Recently the atmosphere had taken on a
new complexity and interest as an electrical
medium, in which connection lightning, thunder,
auroras, meteors, earthquakes, and other spectacular
phenomena were studied, as were prosaic events
such as fog and falling weather. W illiam Henly, the
inventor of a good electrometer, urged readers of
the Philosophical Transactions to keep an "electrical
journal" of the weather, as he did. "Let a large-
book be provided, and ruled in the manner of a bill-
book, used by tradesmen . . . ." The entries in the
columns were the same as in the usual weather
journals except for a new measurement, the diver-
gence of the balls of an electrometer, and a new ob-
servation, the kind of electricity. Henly recom-
mended one other new standard meteorological
measurement, taking the temperature of the upper
air, for which Henly thought that Lord Charles
Cavendish's self-registering minimum thermometer
would serve, carried as high as possible by kites,
frequently and in all kinds of weather. 2 ' 1 At the
time Henry Cavendish took up meteorology, the
kind of record that Henly called for, journals-' 7
instead of isolated w eather reports, began to appear
more often in the Philosophical Transactions. It was a
means to the end, if realizable, as the weather-
journal enthusiast William Borlase put it, of "more
perfect Theories of Wind and Weather in our
Climate." 28 What Charles Hutton wrote in his
scientific dictionary at the end of the eighteenth
century could have been said at any time during
the century:

There does not seem in all philosophy any thing of
more immediate concernment to lis, than the state
of the weather .... To establish a proper theory of
the weather, it would he necessary to have

registers carefully kept in divers parts of the globe,
for a long series of years; from w hence we might be
enabled to determine the directions, bteadth, and
bounds of the winds, and of the weather they
bring with them .... We might thus in time learn
to foretell many great emergencies; as,
extraordinary heats, rains, frosts, droughts, dearths,
and even plagues, and other epidemical diseases.-"'

At once a challenge to science and a vital issue to
humanity, the weather was the kind of problem
that the Royal Society regarded as its reason for
being. Meteorology supported the Society's earlv
Baconian belief in the advancement of science
through natural histories; the "journals," or
"registers," of the weather submitted to the Royal
Society and published in its Philosophical 'Trans-
actions were histories of the weather at different
locations. 'The model was the Royal Society's own
new weather journal, with which Cavendish had
much to do.

The Royal Society called on Cavendish's
skill with meteorological instruments again in 1773,
this time to draw up a plan for taking daily mete-
orological readings by the clerk of the Society. 30
'The first thing in the morning and again at midday
the clerk was instructed to read the barometer and
nearby indoor and outdoor thermometers, and
every morning he was to measure how much rain

Z4 Benjamin Martin, A Description of the Nature, Construction* and
Use of the Torricellian, or Simple Barometer. W illi a Scale nf Rectification
(London. 177K). 3.

^Middlcton, History of the Barometer, 196-97; History of the
Thermometer, 136.

-''•William Henly, "An Account of Sonic New Experiments in
Electricity . . .," PTM (1774): 389-431, on 426-27.

''Charles Hutton. Mathematical and Philosophical Dictionary, 2
vols. (London. 1795-%) 2:667-6K. listed the persons who published
weather journals in the Philosophical Transactions from the late
seventeenth century to the end of the eighteenth, and he gave an
account of the Royal Society's own journal. Mis purpose was to

encourage the keeping and printing of similar registers in other parts

of the w orld. From the 1770s, for the next twenty years, there w as a
revival of interest in meteorology in Europe, owing to the presumed
connections between weather and health and agriculture, and also to
the connection with experimental science: according to Theodore S.
Feldman, "Late Enlightenment Meteorology," in The Quantifying
Spirit in t/ie Eighteenth Century, eds. T. Frangsmyr, J. L. I leilbron, and
R. E. Rider (Berkeley: I'niversitv of California Press. 1990), 143-77.
on 153, 161.

-"J. Oliver, "William Borlase 's Contribution's to Eighteenth-
Century Meteorology and Climatology," .\mwk of Science 25 (1969):
275-317. on 291.

-"'Hutton, Dictionary 2:677.

"'The council ordered that the clerk of the Society make daily
observations of the weather "w ith the instruments to be procured for
that purpose. & proper accommodations under the inspection of the
Hon Henry Cavendish." Royal Society, Minutes of Council. 6:197
(22 Nov. 1773).

Tools of the Trade

165

had fallen, every afternoon estimate the wind, and
one fortnight a year consult the dipping needle
four times a day. With regard to the thermometer
readings, the clerk was also expected to calculate a
rather complicated series of means of readings.
Cavendish proposed that all of this information be
printed at the end of the last part of the
Philosophical Transactions for each year; this was
done beginning with the weather for 1776. 31 So that
the members did not have to wait to the end of the
year to learn what the weather was, the clerk was
ordered to post the previous week's weather in the
public meeting room of the Society.'- Three years
later, at a time when the council was preoccupied
with instruments, those of the Royal Observatory"
and its own, 34 and expanding the instruments used
for the Society's meteorological register,' 5 Cav-
endish was named head of a committee to review
the entire body of meteorological instruments of
the Society. The committee included Heberden,
who, as we have seen, kept a meteorological
journal, Maskelyne and Aubert, who as astronomers
necessarily concerned themselves with the weather
and also constantly with instruments, Samuel
Horsley, regarded by some as the "head of the
English mathematicians"- 56 and an astronomer and
avid observer of the weather, the secretary of the
Society Joseph Planta, and the most important
member other than Cavendish, the meteorologist
Jean Andre Deluc. 37 Deluc was a Swiss who had
recently settled in London, where he took a
position as reader to the queen. Just before his
move, in 1772, he had published an influential
work calling for the perfection of thermometers,
Recherches sur les modifications de T atmosphere, on
T/ieorie des Barometres et des Thermomitrts. 38 In the
committee Cavendish took on Deluc by firmly
endorsing the cistern barometer over the siphon
type, which Deluc championed. Two important
publications came out of this study of the Society's
meteorological instruments, a paper by Cavendish
alone in 1776 and one by the committee in 1777.
The committee's paper was also written by
Cavendish, at least in part, as we know from his
manuscripts. What Cavendish said in his paper of
1776, in connection with the adjustment of the
boiling point of water on thermometers, applies to
his whole effort in meteorology:

It is very much to be wished, therefore, that some
means were used to establish an uniform method

of proceeding; and there are none which seem
more proper, or more likely to be effectual, than
that the Royal Society should take it into
consideration, and recommend that method of
proceeding which shall appear to them to be most
expedient. 39

The recommendations followed in the paper of the
committee the next year. 4 " The study of the
instruments of the Royal Society was a means to a
greater end, the improvement of the accuracy of
science through an agreement among practitioners
on how to use them. Cavendish insured that the
authority of the Royal Society was put behind this
effort. Like every serious worker in meteorology.
Cavendish would have agreed with Richard Kirwan
that no other science required "such a conspiracy
of nations," 41 which entailed a uniformity of
practice around the world.

The recommendations of the committee in
1777 for keeping the Society's meteorological
journal were largely taken from Cavendish's report
to the council in 1773. They repeated, for example.
Cavendish's instructions to the clerk of the Society

11 "Meteorological Journal Kept at the I louse of the Royal
Society. In Order of the President and Council." PT 67 (1777):
357-84.

,2 "The Following Scheme Drawn up by the Hon. Henry
Cavendish for the Regulating the Manner of Making Daily
Meteorological Observations by the Clerk of the Royal Society . . .."
Royal Society. Minutes of Council 6: 20(1-4 (9 Dec. 1773).

"In the mid 1770s Maskelyne and the Royal Observatory took
up most of the time of the council. Cavendish was involved with the
instruments of the Observatory as he would be with the Society's
instruments. Cavendish, Maskelyne. Aubert, Shepherd, and
Wollaston were appointed to a committee to examine two new
equatorial sectors, which had imperfections due to the neglect of the
instrument-maker. Royal Society. Minutes of Council. 6: 280 and 283
(14. Sep. and 12 Oct. 177.S).

'♦Cavendish, Aubert, and Nairne were appointed a committee
to "examine into the state of the Society's instruments." Royal
Society, Minutes of Council, 6:313 ( 14 Nov. 1776).

" The council ordered that once-daily observations with John
Smeaton's hygrometer be added to the Society's meteorological
observations. Royal Society. Minutes of Council. 6:287 ( 16 Nov. 1773).

"'This description is by John Playfair. The Works of John I'layfair,
ed. J. O. Play fair, 4 vols. (Edinburgh, 1822) happendix no. 1,
"Journal," Ixxix.

"Middleton. History of the Thermometer, 127.

iK Middlcton. History of the 'Thermometer, 116-17. Douglas W,
Frcshfield and II. K Montagnier, 'The Life of Horace Benedict De
Saussure (London: Edward Arnold, 1920), 176-77.

'''Cavendish, "An Account of the Meteorological Instruments."

115.

J "Signed by Cavendish (listed first), Heberden, Aubert, Deluc.
Maskelyne. Horsley, and I'lanta: " The Report of the Committee
Appointed by the Royal Society to Consider of the Best Method of
Adjusting the Fixed Points of Thermometers; and of the Precautions
Necessary to Be I'sed in Making Fxperiments with Those
Instruments," / J 7'67 ( 1 777): 816-57.

" Kirwan, An Estimate of the 'Temper/Mire of Different Latitudes, iv.

166

Cavendish

to consult the dipping and horizontal needles for a
fortnight each year, but the clerk was now to make
five observations a day instead of four. This kind of
activity was incredibly tedious, though the
maximum and minimum instruments made the
routine somewhat less confining. Fully automatic
clock-driven registers were the natural solution and
already an old idea. Christopher Wren in the
previous century had proposed a "weather clock,"
and Robert Hooke had developed it into a
futuristic meteorograph using punches on rolled
paper. But it would have been just as tedious to
count the punches, and there were other reasons
why a universal weather instrument was
impractical. 4 -' Cavendish's thoughts turned in the
direction of a clock-driven single instrument, a
thermometer. I le drew plans for an elaborate
mechanical contrivance for recording the tem-
perature every ten minutes on a rotating barrel. 45 It
probably was built, but neither it nor anything like-
it was recommended for the Royal Society, where
only the best of the tried and true instruments
were used. In addition to the thermometer, they
were the barometer, rain-gage, Smeaton's hygro-
meter, Gowin Knight's variation compass made by
Nairne, and John MichelPs dipping needle also
made by Nairne. Cavendish discussed the "error of
observation" and the "error of the instrument" in
achieving "accuracy" in the recording of the
weather. That was done in part by the indoor and
outdoor placement of the instruments, the funnel
collecting rain raised above the roof of the Society's
house where there seemed "no danger of any rain
dashing into it," the hygrometer sheltered from the
rain but open to the wind "where the Sun scarce
ever shines on it." 44 It was done too by taking the
mean of observ ations and by applying corrections,
such as Cavendish's corrections for the thennometer
if the stem is cooler than the bulb, Deluc's rule for
correcting the barometer by the thermometer, and
by a table giving capillary depressions of the
mercury standing in the tube of the barometer.
That table, Cavendish pointed out, was made by
his father. Lord Charles Cavendish. 45 Accuracy was
achieved in still another way, by modifying
instruments; the vibration of the needle of the
variation compass was prevented from disturbing
the observation of the needle, an improvement
which Cavendish credited to his father. 4 '' The
published paper on the meteorological instruments

of the Royal Society was, among other things, a
display of the instrumental prowess of father and
son. The unpublished papers of Henry Cavendish
pertaining to the work on the Society's instruments
are further testimony of the connection between
the two. In 1776-77, Henry Cavendish made end-
less trials with "father's thermometer"; after his
publication on the meteorological instruments of
the Society, Henry Cavendish went right on with
his trials of instruments at the Society, including his
father's. 47 Experiments on the variation compass
and the dipping needle were done far from the
disturbing iron work of the Royal Society's house,
in a "large garden" of a house on Marlborough
Street, which had to be the house where the
Cavendishes lived. 4 * From various of Cavendish's
records of observ ations, we conclude that w hatever
else Cavendish's garden might have contained, it
was abov e all a garden of instruments.

The Cav endish garden is, in fact, the setting
of our last example of Cavendish's work on instru-
ments. Like the weather, the earth's magnetism
varies complexly from place to place and from time
to time, periodically and secularly. Cavendish
observed the earth's magnetic variation and dip at
regular intervals and calculated their mean yearly
values. Before his study of the Royal Society's
meteorological instruments, in the early 1770s,
I Ienry and his father alternated in taking magnetieal
readings with a horizontal needle in the "garden."
"Father" and "self label two columns: on certain
days, one would take a number of readings, on other
days the other. Mixed in with Cavendish's readings

42 Middleton, Invention of the Meteorological Instruments, 254-55.

"Henry Cavendish, "Clock tor Keeping Rc^istc-r of Thermo-
meter." Cavendish Mss IV, I. He made a carefully ruled drawing to
scale of this instrument, probably for his instrument-maker.

"Cavendish, "An Account of the Meteorological Instruments," 117.

4S Cavcndish, "An Account of the Meteorological Instruments,"
1 16-17. Charles Cavendish's table gave the depression of mercury in
inches corresponding to tubes of bores between 0.1 and 0.6 inches;
for the largest bore, the depression was extremely small. 0.005
inches. This table had a long history after its publication by Henrv
Cavendish; in the theory of capillarity, it w as cited by Thomas Voting
and by Laplace after the turn of the nineteenth century. Middleton,
The History of the /{urometer, 1 KK-H9.

^Cavendish, "An Account of the Meteorological Instruments," 120.

47 Two packets of Henry Cavendish's papers are headed " Trial of
Boiling Point with Father's 'Thermometer." one with 33 numbered
pages, one with 4: Cavendish Mss 111(a), 10 and 11. In addition, in
packets labeled "Expansion of Steam" and Theory of Boiling," there
are more readings taken with his father's thermometer in 1777 at the
Royal Society, ibid. 111(a). 5 and 13.

JH I Ienry Cavendish, "Horizontal Needle." Cavendish Mss IX. 4.

ghted malarial

Tools of I he Trade

167

are others taken by Heberden at Heberden's house
and also, it would seem, in Cavendish's garden. 49
Upon moving from his father's house, Henry
Cavendish kept a reeord of variations of the magnetic
compass at Hampstead from 1782 and then from
Clapham Common until 1809, the year before he
died. This record consists of more or less daily
readings through the summer months. 50 The
timing may have had to do with the weather, since
Cavendish took several readings a day beginning
before eight in the morning and ending about
eleven at night; it may have had to do with his
habits, too, since in the summer the Royal Society
was not in session, and the summer was otherwise
a good time to be constantly outside London.
Cavendish did not place much weight on these
readings, for when he was asked about the mean
variation of his observatory at Clapham Common, he
gave it for the past summer but not for past years,
since, he said, many others there had observed the
variation longer than he had. 51 (Cavendish's
scientific company at Clapham Common included
the Evangelicals who made that suburb famous in
his time.) His interest centered on the instruments
and their method of use. Because the magnetism of
the earth draws the needle not only roughly north
but also down, there are two kinds of instruments:
in addition to the variation compass, there is the
dipping needle, which Cavendish subjected to
countless experiments and computations concerning
suspensions, shapes, and sizes; he tried his father's
dipping needle and Sisson's and Nairne's, and he
designed his own, and he drew up directions for
using the dipping needle on several voyages. 52

We have chosen meteorology as our main
source of examples to illustrate Cavendish's way of
using instruments. Whoever reads through his
papers on this subject must be impressed by the
tenacity with which he compared his instruments
among themselves and with those belonging to the
Royal Society and to Nairne and other individuals.
For ten years he compared the instruments for
measuring the moisture of air, hygrometers, whose
inventors disputed with their rivals so heatedly that
Charles Blagden spoke of their "open war," 53 and
yet they and Cavendish all agreed on what one of
the inventors J. A. Deluc called the "essential point"
about the hygrometer; namely, that all "observers
might understand each other, when mentioning
degrees of humidity." 54 Another inventor John

Smeaton put it best: the goal was to construct
hygrometers that, like the best thermometers, were
"capable of speaking the same language." 55
Cavendish tried "Smeaton's" hygrometer used by
the Royal Society, and other hygrometers labeled
variously "Nairne's," "Harrison's," "Coventry's,"
"common," "old," "new," "4-stringed," and "ivory."
The general type of instrument he studied was
the hydroscopic hygrometer, which either weighed
the water (he weighed the increase in weight of dry
salt after moist air was passed over it) or measured
the change in dimensions of a moistened substance
such as the contraction of strings (he preferred this
method, in contrast to our preference today for
weighing). He roasted, salted, wetted, and stretched
the moisture-absorbing strings, and he mixed
vapors from acids and alkalis with the air to see if
that made a difference. At times he made readings
daily, morning and evening, as often as every twenty
minutes, in warm rooms and cold rooms, often
together with thermometer readings. 5 ' 1 If this activity
sounds obsessive, we need to remind ourselves that
it went to the heart of the work of science. In any
experimental investigation, the reliability and
the errors of instruments and their method of
use were an inseparable part of the scientific
argument. It could be said, and Cavendish could
have said it, that an unexamined instrument was
not worth using.

4<, Cavcndish. "Horizontal Needle." On p. 3, alongside
Cavendish's readings taken in his garden, there is a list of readings by
Heberden, who must have been there too. Cavendish's manuscripts
also contain readings of the variation compass taken at Heberden's
house: Cav endish Mss IX, 19, 21, 23.

s "Hcnry Cavendish, "Observations of Magnetic Declination,"
Cavendish Mss IX, 1. The earliest observations in this manuscript of
256 numbered pages were made at Hampstead; those from p. 30 on
were made at Clapham Common.

■■'Henry Cavendish to J. Churchman, n.d. /1793/. draft.
Cavendish Mss, New Correspondence.

'-'Some of the manuscripts are Henry Cavendish's instructions to
an instrument-maker. "Dipping Needle"; "Trials of Dipping
Needles"; and "On the Different Construction of Dipping Needles,"
Cavendish Mss IX, 7, 11, and 40. He drew up directions for the use
of the dipping needle for three voyages, by Richard I'ickergill, James
Cook and William Bayley, and Alexander Dalrvmple: Cavendish Mss
IX, 41, 42. 43.

"On Saussure and Deluc's disagreements: Charles Blagden to
Henry Cavendish, 23 Sep. 1787, Cavendish Mss X(b). 14.

S4 Jcan Andre Deluc. "Account of a New Hygrometer," PT 63
(1773): 404-60, on 405.

55 John Smeaton. "Description of a New Hygrometer," PT 6]
(1771): 198-211, on 199.

'•Henry Cavendish, "Hygrometers," Cavendish Mss IV, 5. This
manuscript consists of 77 numbered pages of laboratory notes and
an index.

168

Cavendish

The work of the maker of scientific
instruments and that of their user went hand in
hand, in a complementary way. 57 Earlier it had been
common for scientific researchers to make their
own instruments, but in Cavendish's day it was
common for researchers to build their apparatus
but to buy or commission their instruments.
Researchers still invented instruments and
instrument-makers like Nairne still did experi-
ments, but instrument-making was a business, and
science for someone like Cavendish was pretty
much full time. Virtually every one of Cavendish's
instruments was made in London by a con-
temporary, highly skilled instrument-maker. This
most precise of experimenters lived at the time of
the world renow n of London instrument-makers. 58
His achievement in science gives substance to the
adage: being in the right place at the right time.

We close this discussion by paying tribute
to British instrument-makers as it was then done.
Cavendish's exhaustive work on instruments was
an implicit form of tribute. His colleague George
Shuckburgh made the tribute explicit, remarking
on the "singular success with which this age and
nation has introduced a mathematical precision,
hitherto unheard of, into the construction of
philosophical instruments. " s '' In his living quarters
at Greenwich Observatory, the astronomer royal
Nevil Maskelyne exhibited in addition to a bust of
Newton prints of the builder of the great eight-foot
mural quadrant for Greenwich, John Bird, and of
the inventor of the achromatic telescope used at
Greenwich, John Dolland/ 1 "

; Mathematics

Mathematics, the mathematical teacher and
instrument-maker Benjamin Martin wrote, is "the
science or doctrine of quantity." M It is a subject that
we might expect Henry Cavendish to take an
interest in, and we would not be wrong. His
manuscripts on mathematics are as numerous as
those on astronomy or magnetism or mechanics.
He did not publish any of his work on
mathematics, raising the question of why he did it.

Mathematics clearly held an interest of its
own for Cavendish, as is shown by a paper on
prime numbers''-' and by other papers on topics that
interested mathematicians of that time. These
include papers relating to De Moivre's work, such
as the probability of w inning more than losing in a

game, the probability of throw ing a certain number
with a certain number of dice, the possible ways of
paying a sum with coins of different denominations,
and annuities on lives/' 3 There are papers on the
binomial theorem, the multinomial theorem,
infinite series, and the construction and solution of
algebraic equations/' 4 There are still other papers
that have a direct bearing on Cav endish's scientific-
work; e.g., on Newton's rule of interpolating, on
the accuracy of taking the mean of observations, on
triangular forms that reduce the effects of errors of
measurement, and on the errors of instruments/' 5
The bulk of Cavendish's mathematical papers deal
with problems relating to plane or spherical
geometry. Some of these are purely mathematical
in interest, for example, extremal problems (the
greatest cube that can pass through a hole in another
cube), and some have scientific implications (a curve
drawn with reference to three points)/' 6 The next
to longest of his mathematical papers deals with a
geometrical problem of William Braikenridge, a
London clergyman and f ellow of the Royal
Society/' 7 His longest mathematical paper is about
the loci of equations of the third order (equations,
like plants and animals, were classified into
"orders," "classes," genera," and "species")/' 8 Both
of these long papers, and many of the other
mathematical papers, fall late in his life, when he

57 The intimacy of instrument-makers anil scientists of this time-
is remarked on in Taylor, Mathematical Practitioners., 43, 58.

^From 1760, when Cavendish entered the Royal Society, to
1780, the instrument-makers of London were at the height of their
world tame, according to Taylor. Mathematical Practitioners, 43.

5, George Shuckburgh, "On the Variation of the Temperature of
Boiling Water." PT 69 (1779): 362-75, on 362.

'■"Visitations of Greenwich Observatory, 1763 to 1815, Royal
Society. Ms. 600, XIV.d.1 1, f. 36 (29 July 1 785).

'■'Benjamin Martin. A Mnr and Comprehensive System of
. Mathematical Institutions. Agreeable to the Present State of the Sea: Ionian
Mathesis, 2 vols. (London, 1759-64) 1:1.

''-Henry- Cavendish. "On Prime Numbers," Cavendish Mss
Vila), 8.

'■'Cavendish MssVKa). 1. 25. 46. 48.

'-'Cavendish Mss Yl(a), 15, 16, 21, 22, 24. 27.

65 Cavendish Mss Vila), 6, 34, 45. 'The paper on the probable-
error of instruments does not have a catalogue number. The problem
it addresses is: to determine the probability of the sum of the errors
of two instruments given the error of any one instrument.

"Cavendish Mss. VI(a) 17. 36.

67 Braikenridge's problem has to do with a surface in three
dimensions, generated by the line joining two points moving
uniformly along two lines not in the same plane. Fifty-two-page
manuscript: Henry Cavendish. "On Dr. Braikenridge 's Surface,"
Cavendish Mss VI(a), 12.

' ""On Some Properties of Lines of the 3rd Order & on the Loci
of Equations of the 3rd Order." Seventy-page manuscript: Cavendish
MssVKa). 19.

Copyitghied malarial

Cavendish

theory of the cause of the magnetism of the earth.
In chemistry, as we have seen, he worked out a
general theory of metals within the framework of
the phlogiston theory, but he did not make it
public. He had theoretical notions about the cause
of chemical reactions at the level of particles and
forces, but he was far from being able to develop
this approach sufficiently to give chemistry its
general theory. In astronomy and optics, there were
already successful general theories, that of gravitation
and, though it was less complete, the corpuscular
theory of light. In a subject that combined heat,
gases, and vapors, Cavendish worked out a special
theory to explain boiling. He worked out only two
original, general theories, and only one of these he
published. The theory he did not publish was on
heat, which he developed from another, existing
theory, that of motion. The theory he did publish
was on electricity. We discuss Cavendish's early-
theory of heat and his early and mature theories of
electricity below.

We need to clarify a point of mechanics at the
start. 7<) We assume that by the time Cavendish left
Cambridge, in 1752, he was thoroughly at home
with Newtonian mathematical principles of natural
philosophy. For the purposes of this discussion it is
sufficient to recall that in Newtonian mechanics,
the measure of the quantity of motion of a body is
the product of the body's mass and velocity, or
momentum. At some point, undoubtedly at
Cambridge, Cavendish became familiar with
another formulation of mechanics, originating with
Leibniz, in which the quantity of motion of a body
is taken to be vis viva, the product of the mass and
the square of its velocity (a quantity close to our
kinetic energy). Leibniz and his followers regarded
vis viva as a conserved quantity, incapable of
disappearing without giving rise to a comparable
effect, an equal quantity of potential motion. This
understanding was well suited for the treatment of
a range of mechanical problems, but it encountered
difficulties in the treatment of collisions between
bodies. It was known from experience that
collisions are never perfectly elastic, which means
that vis viva is lost. But because the belief in
conservation was unshakable, the missing vis viva
was regarded as only apparently lost, as continuing
on in hidden forms such as the compression of
bodies or the motion of parts internal to bodies.

Leibniz proposed the latter explanation, but he did
not identify the hidden vis viva with heat, even
though in his day heat was commonly believed to
be the internal motion of bodies. It would seem
that the conceptual problems of treating heat as a
quantity made this identification difficult/"

By the time Cavendish began his indepen-
dent studies, it was customary to assume that for
isolated mechanical systems the sum of the actual
and hidden vis viva is constant. To uphold the
validity of the conservation law, various explana-
tions for the lost vis viva were entertained, though
experiments to measure the vis viva so transformed
had not been proposed. (It would be nearly a
century later, in the middle of the nineteenth
century, before the identification was established
between the mechanical motion lost or work
performed and an equivalent quantity of heat. This
became the first law of a new theory, the mechanical
theory of heat, or thermodynamics, and it was
extended to all forms of energy to become the
completely general law of conservation of energy/ 1 )
We know from Cavendish's manuscripts
that he intended to write a book largely dealing
with the theory of motion. "Flan of a Treatise on
Mechanicks" is the thirty-odd-page beginning,
probably written in 1763 or soon after, making it
one of the earliest of his surviving writings. 8 -'

7 ''This account of Cavendish's theory of heat is taken from
Russell McCormmach, "Henry Cavendish on the Theory of Heat."
Isis 79 (1988): 37-67. Sec pt. 4, ch. 4. n. 24.

""Krwin N. Hicbert, Historical Roots of the Principle of Energj
Conservation (Madison: State Historical Society of Wisconsin, 1962),
80-93; anil I'. M. Heimann, '"Geometry and Nature': Leibniz and
Johann Bernoulli's Theory of Motion," CentaurusZ\ (1977): 1-26.

s'Hiebert, Historical Roots, I. 5, 60, 95, 102. Larmor calls
attention to Daniel Bernoulli's writings, which provide an exception
to the general rule that vis viva was not identified with heat: in
Cavendish, AW. Pap. 2:408. 424.

* 2 llcnry Cavendish, "I'lan of a Treatise on Mechanicks,"
Cavendish Mss IV(b). 45. The "Plan" is important for establishing
the connections between Cavendish's various researches. No date is
given in the manuscript, but Hugh Hamilton is mentioned in it for
his discussion of the lever; Hamilton published on that subject in the
Philosophical Translations for 1 763. The watermarks on the paper of
the "Plan" — I IT. CR, and ProPatria — point to an early date, not long
after that year. I IT, which rarely appears on the paper Cavendish
used, appears on the paper of a theoretical manuscript, "Concerning
Springs." which belongs to the subject of the "I'lan." and again on
the covering paper of the manuscript "Digression to Paper on
Inflammable Air." which belongs to 1766. The other two watermarks
appear in combination in the manuscript "Experiments on Factitious
Air." which also belongs to 1766, and in experimental notes on the
specific and latent heats, which bear the earliest date of 1765; these
two watermarks are compatible with but do not demand an early-
dating, since they also appear in much later work. Taken together,
the evidence argues for placing the "Plan" in the mid- 1760s.

ghied maierial

Tools of the Trade

171

Concerned with the logical and empirical founda-
tions of mechanics, the "Plan" is similar in nature
to works that Cavendish read at Cambridge, and as
such it reveals more about his formal education than
about the original investigator he was to become.

The "Plan" is divided into two parts. The
first treats the doctrine of pressures and mechanical
powers, beginning with the lever. The second treats
the theory of motion. There Cavendish argued that
what Newton called the third law of motion is only
a property of the doctrine of pressures and that all
we know of the properties of matter in motion is
contained in the first two laws. The foundation of
Newton's third law of motion — to every action
there is an equal and opposite reaction — was a deep
question of mechanics, and there was a decided
suggestion in Newton's applications of the law that
it had for him a metaphysical, a priori foundation. 83
Cavendish's critical analysis of the logical
foundations of mechanics and an enumeration of
the experimental proofs of the laws of motion
constitute the "Plan," so far as it goes.

Cavendish developed the theory in original
directions in separate, unpublished papers, the
most important of which is "Remarks on the
Theory of Motion." Typical of his theoretical
papers, this one is undated, but there is good
reason to think that it too falls early in Cavendish's
work, especially when it is compared with his
datable experiments on heat, which would place it
no later than 1765. H4 If the "Remarks" originated in
the "Plan of a Treatise," they took another
direction, leading to questions that only research
outside of mechanics proper could answer. The
purpose of the "Remarks" was to show the
usefulness of vis viva as a "way of computing the
force of bodies in motion." For most questions
arising in "philosophical enquiries," Cavendish
acknowledged that the usual and most convenient
way of computing the forces was Newton's
momentum and that vis viva was usually reserved
for solving problems concerning machines for
"mechanical" purposes. (The mechanical engineer
John Smeaton wrote about vis viva for engineers,
and he gave his writing on the subject to
Cavendish for comment.* 5 ) But vis viva had
"philosophical" uses, too, Cavendish said, as he
went on to show, though instead of "vis viva" he
preferred to speak of the "mechanical momentum"
of bodies in motion. By this choice of terminology,

referring to both ways of computing the force as
species of "momentum," Cavendish drew on his
conviction that the choice of one way or the other
was a matter of convenience, not of fundamentals. 8 ''
Force itself was the fundamental thing, not the
way it was measured.

"'Roderick W. Home, "The Third Law in Newton's
Mechanics," British Journal for the History of Science 4 < 1 968): 39-5 1 ,
on 42,51.

M ln a theoretical discussion of heat in the "Remarks,"
Cavendish showed no awareness of specific and latent heats, which
he began experimenting on no later than 1 765.

Both the subject and the watermarks of "Remarks" favor an
early date. The theory of motion continues the project of the "Plan,"
Cavendish's intended treatise on mechanics. One of the watermarks,
LVG, appears on the earliest of Cavendish's extant papers, his
calculations for the 1761 transit of Venus; its last datable appearance-
is on a paper of 1781. The other watermarks, CR without a circle and
an emblem bearing the word "Kropa," appear also on the manuscript
"Thoughts Concerning Electricity," which was written sometime
between 1767 and 1771; on two manuscripts concerning pendulums;
on three astronomical manuscripts, two of which are calculations for
the transits of Venus of 1761 and 1769; and on three manuscripts on
arsenic, which a given date places in and around 1764, the earliest ot
Cavendish's datable chemical researches. These correlations strongly
suggest that "Remarks" was written in the 1760s and so is among
Cavendish's earliest surviving scientific papers.

w John Smeaton published several papers in the Philosophical
Transactions in which he argued that vis viva is a measure of
mechanical power. He also argued that mechanical power can be lost,
as in the turbulence of water in the working of a water wheel.
Without specifying the circumstances of the problem at hand, he
said, "the terms, quantity of motion, momentum, and force of bodies
in motion, are absolutely indefinite." Smeaton, "An Experimental
Examination of the Quantity and Proportion of Mechanic Power
Necessary to Be Employed in Giving Different Degrees of Velocity
to Heavy Bodies from a State of Rest," PT 66 (1776): 450-75, on 473.
The paper Smeaton gave Cavendish to comment on was probably
"New Fundamental Experiments upon the Collision of Bodies," /'/'
72 (1782): 337-54. John Playfair told Smeaton that foreign
mathematicians already knew about vis viva in the way he was using
it. Smeaton answered that it was not known by engineers, his
intended audience, and that if his conclusion about collisions was not
new, his experiments were. On one point, Playfair made Smeaton
"very happy": he told Smeaton that "what he said was no way
inconsistent with the New tonian doctrine of motion." Playfair. Worts,
ld.xxxiii-lxxxiv.

"'' There had been a protracted controversy over the true
measure of force, Cavendish siding with the position taken by Jean
d'Alcmbert and others. Momentum and vis viva, he said, are two
ways of measuring the same thing, the force of bodies in motion: "It
appears therefore that this famous controversy about the force of
bodies in motion was merely a dispute about words the 2 sides
meaning different by the expression force of bodies in motion, for if
you measure the force of a body in motion by the time during which
it will overcome a given resistance or by the degree of resistance
which it will overcome during a given time then this force is directly
as the velocity of the body. But if you measure this force by the
space through which it will move against a given resistance or by the
degree of resistance against w hich it will move through a given space
then its force is as the square of its velocity." This quotation forms
the conclusion of an unnumbered four-page addition to "Remarks."
It was not published with the "Remarks" in Cavendish's Scientific
Papers, but it has since been published and analyzed in P. M.
Hcimann and J. E. McGuirc. "Cavendish and the Vis viva
Controversy: A Lcibnizian Postscript," IsishZ (1970): 225-27.

172

Cavendish

Plate III. Forces. The dashed lines represent fortes of attraction and repulsion of constant intensity surrounding particles of matter, or force cen-
ters. A and I). BC in Figure 2 and Bb in Figure 3 are the paths of a second attracting and repelling particle. With the aid of these diagrams and a
proposition from Newton's I'rincipia. Cavendish argues for his general law of conservation of the sum of "real" and "additional" "mechanical
momenta" (our kinetic and potential energy). It has been pointed out that Cavendish is struggling here with our concept of cquipotcntial curves.
"Remarks on the Theory of Motion." ( lavendish Mss VI(b), 7:plate 3; The Scientific Papers of the Honourable Henry Cavendish, F.K.S., vol. 2: Chemical
anil Dynamical, ed. K. Thorpe (Cambridge: ( lambridgc I nivcrsity Press. 1921 ). 430.

As in the "Plan of a Treatise," in the
"Remarks on the Theory of Motion," Cavendish
started with the lex er and the motions of simple
machines. He then examined, ease by ease, elastic
and inelastic collisions, progressing to the more
difficult problems involving any number of bodies
attracting or repelling one another by forces. He
concluded that, assuming the forces are "central"
and act equally at equal distances from their
centers, "whenever any system of bodies is in
motion in such a manner that there can be no force
lost by friction imperfect elasticity or the impinging
of inelastic bodies, that then the sum of the
mechanical momenta of the moving bodies added
to the sum of the abovementioned additional
momenta will remain constantly the same."" 7 The
"additional momenta," in contrast to the "real
momenta," represented the hidden, or potential,
mechanical momentum temporarily stored in
elastic compression or gravitational elevation.
Cavendish's statement of the conservation law had
a most general character. It speaks of Cavendish's
point of departure in mechanics that in reasoning
to his law of conservation (of energy), he cited a
proposition, number 40, from Newton's Principia
and nowhere mentioned Leibniz, or other Con-
tinental dev elopers of the mechanics of vis viva.

Heat is identified in "Remarks on the Theory
of Motion" with the vibrations of the particles of
which the large bodies of our experience arc com-
posed. That much Newton and his contemporaries

had said. Cavendish went further by making the
mechanical understanding of heat mathematically
precise: heat, Cavendish said, is the mechanical
momentum of the vibrating particles. He related
his theoretical conserv ation law to an empirical one,
the familiar rule that when two unequally heated
bodies are placed in contact, the heat lost by one
equals that gained by the other: one body receives "as
much mechanical momentum or in other words as
great an enerease of heat multiplied into its quantity
of matter as the other loses so that the sum of their
mechanical momenta may remain unaltered." 88

Cavendish showed that mechanical momen-
tum applies to other areas outside of mechanics in
addition to heat. Representing air as a perfectly
elastic, particulate fluid, he analyzed the motion
constituting sound; and by analogy with sound
waves in air, he analyzed waves in water. He dis-
cussed light, another particulate body, which com-
municates its mechanical momentum to absorbing
bodies in the course of internal reflections, heating
them. And so, over a range of problems belonging
to mechanics, heat, acoustics, hydrodynamics, and
optics, Cavendish in his "Remarks on the Theory
of Motion" demonstrated the value of computing
the forces by mechanical momentum when taken
together with its conservation law. 8 ''

"'Cavendish, "Remarks," 428.
""Ibid. 424-2.S.
"'Ibid. 421,426-27.

Tools of the Trade

For all of its promise, however, the mechan-
ical theory of heat was in itself incomplete. The
explanation of the transfer of heat between bodies
could not account for the generation of heat and
cold accompanying certain chemical and physical
changes in bodies. Cavendish observed that

there is plainly both an encrcase and loss of heat
without receiving it from or communicating it to
other bodies, as appears from the fermentations
and dissolutions of various substances in which
there is sometimes an encrease sometimes a loss
of heat as well as from the burning of bodies in
which there is a vast encrease of heat above what
can reasonably be supposed to be produced by the
action of emitting light.

Newton too had spoken of the emission of light
and its internal reflections and refractions as
causing bodies to heat, but Cavendish did not
think that this source could account for the great
heats observed in combustion. And Newton too
had singled out fermentation, dissolution, and
burning as evidence of the action of attractive
forces, causing particles to collide with violence,
manifesting heat. Newton had evidently been
mistaken. Cavendish denied that the uncommon
heats could arise from the approach or recession of
the particles, increasing their motion at the expense
of their "additional" momenta, which led him to
consider other explanations:

Particles must either not attract or repel equally at
equal distances or must act stronger when placed
in some particular situations than others or
something else of that nature. One would be apt
at first to explain this by supposing them to attract
or repel some kind of bodies stronger than others;
but then it should seem as if there should always
ensue an encrease heat whenever 2 bodies are
mixed which mix together with any degree of
force whereas there is often produced a great
degree of cold thereby as in mixing salt and water.
There are other reasons too which seem to shew
that this way of explaining it is insufficient. 1 ' 0

So even variable and asymmetrically acting forces,
which violate the assumptions of the conservation
law, could not answer for these heats. Cavendish
had no answer.

Earlier we discussed Cavendish's experi-
mental researches on specific and latent heats of
the 1760s, pointing out that he wrote them up as a
paper to be read, "Experiments on Heat." There is
good reason to place this paper later than the
"Remarks on the Theory of Motion," since it

173

contains a theoretical development originating in
his experiments. Cavendish anticipated that it would
not be obvious to his intended reader how specific
and latent heats can be explained by Newton's
theory of heat, and he concluded the "Experiments
on Heat," with a section headed "Thoughts
Concerning the Above Mentioned Phenomena."
The section contains only one thought, an
incomplete one at that: the foregoing experiments.
Cavendish wrote, "at first seemed to me very
difficult to reconcile with Newton's theory of heat." 91
The proposition to follow, which was to reconcile
the experiments with Newton's theory, is not given.

The proposition Cavendish had in mind
clearly had to do with specific heat and its
relationship to the "additional" mechanical momenta
of the theory. For at the time of the "Experiments
on Heat," Cavendish regarded specific heat as
fundamental and latent heat as derivative. The
heat and cold produced during the change of state
of a substance are explained entirely by differences
in the specific heats of the substance in its three-
states. In Cavendish's words: "The reason of this
phenomenon seems to be that it requires a greater
quantity of heat to make bodies shew the same
heat by the thermometer when in a fluid than in a
solid state, and when in an elastic state than in a
non-elastic state." Cavendish's reasoning enabled
him to begin to resolve the theoretical difficulties
he discussed in the "Remarks on the Theory of
Motion." In a preliminary draft of the "Experi-
ments on Heat," he referred to the cold produced
by the mixture of salt and water, which in the
earlier "Remarks" he spoke of as conttadicting
Newton's theory. Now he said of it that "I very
much question indeed whether there is any real
instance of cold being produced by the mixture of
2 bodies which have an affinity to each other," and
he supposed that it "will be shown to be owing to
another cause." In another experimental note he
said that the "heat caused by mixing spirits &
water is not caused by the commotion made by the
particles of one uniting with those of the other but
only that the mixture of spts & water requires a

'"'Ibid. 425-26.

"Henry Cavendish. "Experiments on Heat" This manuscript of
40 numbered panes and 10 more unnumbered sides on i folded
sheets is in Cavendish Mss, Misc., and is published in entirely in Sri.
Pup. 2:327-51, quotation on 351.

174

Cavendish

greater quantity of heat to make it raise the
thermom. to a given degree than the 2 liquors
separately do." 1 ' 2 To account for the phenomena of
heat. Cavendish now had another quantity to
interpret mechanically in addition to the mechanical
measure of the vibration of particles: the specific
heats of substances and their combinations. The
promised proposition was not given in "Experiments
on I leat" because, we believe, Cavendish found that
the explanation of his experiments required a full,
new theoretical analysis of heat. Twenty years later
he developed this proposition into a complete
version of Newton's theory of heat; we discuss this
theory in a later chapter.

Cavendish carried out fundamental theoretical
studies on dynamics, heat, gases, and electricity
more or less at the same time, in the 1 760s, 93 and
the relationships between these studies are many.
Cavendish began working on his electrical theory
at about the time of his first publication, on
factitious air. This theory was based on the
hypothesis of an electrical fluid, an elastic matter of
electrical particles capable of being bound within
the pores of ordinary bodies. The electrical fluid
behaved, that is, like a factitious air, an analogy
which Cavendish made explicit. Cavendish's
electrical theory was a culmination of his previous
theoretical work in the sense that he carried the
theory of electricity, and that theory only, to a
complete and published conclusion.

In the forty years before Cavendish took up
electricity, the subject had been organized
experimentally into broad classes of phenomena:
attraction, induction, conduction, and so forth. To
appreciate this progress, it is only necessary to
recall the state of the subject when Newton took it
up: to the Royal Society Newton described how
glass rubbed on one side attracts and repels bits of
paper to and from its opposite surface with an
irregular and persisting motion. 1 ' 4 By the 1760s
electricians were beginning to associate electricity
with a force acting ov er sensible distances according
to a determinable law, the starting point of a
systematically quantified field of electricity. The
field was made for Cavendish, skilled manipulator
of instruments and maker of mathematical theories.

If Newton observed only agitated bits of
paper, he nevertheless sensed that electricity could
play a great role in nature. In the Principia he

speculated on an electrical ether, a "certain most
subtle spirit which pervades and lies hid in all gross
bodies." It might, Newton thought, account for the
forces of electric bodies and beyond that for light
and cohesion and animal sensation and will. To
learn the laws of "this electric and elastic spirit,"
more experiments were needed. 95

Through the early eighteenth century, as
techniques were developed for detecting, genera-
ting, and accumulating electrical charges, Newton's
prophesy of the importance of electricity in the
great scheme of things seemed borne out (and, to
some electricians, of his speculation about the
electrical ether as well). The action of electricity
promised to be as universal as that of gravitation
and, as impressively demonstrated by the Leyden
jar, far more powerful. Fifty years after Newton,
the insightful student of the Leyden jar William
Watson observed that electricity was an "extra-
ordinary power" that "cannot but be of very great
moment in the system of the universe."'"' On the
eve of Cavendish's entry onto the scientific scene
as an electrician, Joseph Priestley observed that
electricity was "no local, or occasional agent in the
theatre of the world," that it played a "principal
part in the grandest and most interesting scenes of
nature." 1 ' 7 That was to repeat what Newton had
said, only now with a good deal more evidence.
Scientific expectations ran high. With the exception
of his work for the Royal Society on its projects, for
several years Cavendish devoted himself almost
exclusively to a great work on electricity. He set
out to treat a second force of nature after the model
of the first, gravitation, and he planned a book
about it after his model, Newton's Principia.

In accord with his idea of how theories are
made, Cavendish began with a hypothesis, that of a

,,2 Ibid. 34.5; four-page preliminary draft of the beginning of Part
II of "Experiments on Heat"; and experimental notes on specific
and latent heats. Cavendish Mss 1 1 1(a). 9:39-40.

'' The following discussion of Cavendish's electrical theorv
draws on Russell McCormmach, "The Electrical Researches of
Henry Cav endish." I'hl). diss.. Case Institute of Technology, 1%7.
especially chapter 3. "Cav endish's Electrical Theory," 146-321.

■"Reported in Joseph Priestley, The History and Present State of
Electricity with Original Experiments (London. 1 707). 13-1-4.

,s Isaac Newton. Sir Isaac Newton's Mathematical Principles of
Natural Philosophy and His System of the World, trans A. Motte. rev. F.
Cajori, 2 vols. (Berkeley and Los Angeles: University of California
Press, 1962), 2:547.

■"'William Watson. "An Account of the Phenomena of Electricity
in Vacuo." PTA1 ( 1 752): 363-76 on 375-76.

''"Priestley, The History of Electricity, xii.

Tools of the Trade

IIS

specialized matter of electricity, the electric fluid.
This electric fluid, a common notion then, owed
something to the older idea of electric effluvia but
more to the later idea of a general or electric ether.
Hermann Boerhaave's doctrine of elementary fire
was an influential intermediary between the ether
and the various imponderable fluids of the
eighteenth century. 98 Particulate, active fluids were
postulated for electricity, magnetism, light, and
heat, which all bore the prime characteristic of
Boerhaave's fire: they were bodies "sui generis, not
creatable, or producible de novo."*** For its unity,
simplicity, and grandeur, the general ether held a
strong appeal to experimental philosophers, though
in the middle of the century in Britain, progress in
the exact understanding electricity and heat did
not depend on the concept of the ether directly but
on the related concept of specific fluids of fixed
quantity. Cavendish did not accept a fluid of heat
but he did the fluid of electricity, for particulars of
which he drew upon Watson's and Franklin's work.

Watson was the electrical experimenter with
whom Lord Charles Cavendish worked closest.
The leading British electrician before Franklin,
Watson continued to be regarded as one of the
Royal Society's leading electricians into the period
of Henry Cavendish's researches twenty years later.
His theory of electricity of 1748 was based on an
electric fluid that permeated all bodies, giving no
sign of its presence when the "degree of density"
was everywhere the same; but when there was a
local inequality in density, electrical effects were
manifested as the electric fluid moved to adjust its
density to the same "standard." 100 Watson's fluid
invited the mathematization of electricity, and had
he been a mathematician, he might have
recognized that two quantities have to be specified
to characterize electric phenomena.

In his History of Electricity in 1767, Priestley
said that Fnglish electricians and most foreign ones
too had adopted Franklin's theory of positive and
negative electricity. Priestley's own opinion was that
the basic features of the theory were as "expressive
of the true principles of electricity, as the Newtonian
philosophy is of the true system of nature in
general." 10 ' Franklin defined a body to be
"positively" electrified if it has more than its
"normal" quantity of electric fluid, "negatively"
electrified if is has less. The usefulness of his
terminology is evident in his analysis of the Leyden

jar: one side of the jar is electrified positively in
exact proportion as the other side is electrified
negatively. His theory requires that the amount of
fluid that enters one side must flow out of the other.
Franklin's analysis turns on the quantities of electric
fluid, and although quantity alone is insufficient to
explain all electrical phenomena, it nevertheless
affords a reasonable understanding of the Leyden jar
and of most instances of attraction and repulsion of
electrified bodies.

"Thoughts Concerning Electricity,"
Cavendish's first electrical theory, 10 - cannot be
earlier than 1767, since Priestley's Histoty of
Electricity published in that year is cited in it. Here
again, as in his writings from that time on chemistry
and heat, there is mention of "the reader," who
could be the same reader. Although the paper is
carefully written, it is fittingly labeled "thoughts."
It has a clumsy organization and conveys a sense of
groping, and it certainly is not a final draft of
anything. We learn from it that Cavendish rejected
the commonly held idea of electric "atmospheres"
surrounding bodies, an important element in
Franklin's theory. We also encounter what would
become the leading concept of Cavendish's final
theory, the "compression," or "pressure" (as we
would say), of the electric fluid (which, Maxell ob-
served, means the same as our modem "potential" 103 ).
Pressure is an active concept borrowed from
pneumatics. Cavendish used Franklin's terms
"positive" and "negative" — like Watson's theory.
Franklin's theory too, with his plus and minus
terms borrowed from numbers, pointed toward the

W I. I?. Cohen, Franklin and Newton: An Inquiry into Speculative
Newtonian Experimental Science and Franklin's Work in Electricity as an
Example Thereof (Philadelphia: American Philosophical Society.
1956). 214-34.

'"Hermann Boerhaave, A New Method of Chemistry; Including the
Theory and Practice of 'That Art: Laid Doxri on Mechanical Principles, and
Accommodated to the I 'ses of Life. The Whole Making, a Clear and Rational
System of Chemistry . . .. trans. P. Shaw and K. Chambers. 2 vols.
(London, 1727). 1:233.

'""William Watson. "Some Partner Inquiries into the Nature and
Properties of Electricity," FT 45 (1748): 93-120, on 95.

""Priestley, History of Electricity, 160, 455.

102 Maxwell calls it the first "form of Cavendish's theory": Sec
Pap. 1:397-98. The paper, "Thoughts." is on 110-17.

'"'Maxwell, in Cavendish. Sci. Pap. 1:11 1. The fundamental con-
cept of Cav endish's later electrical theory, the "compression," or as he-
renamed it. the "degree of electrification." was recognized by Maxwell
as being equivalent to our electrical potential. We should recall here that
in his "Remarks on the Theory of Motion," as Larmor pointed out,
Cavendish introduced the equivalent of equipotcntial lines. Cavendish's
original work in dynamics was a direct preparation for his original
work in electricity.

176

Cavendish

mathematization of electricity — but with a different
meaning, associating them not with quantity of
electricity but with his new concept of
compression: he called a body "positively" or
"negatively" electrified according to whether the
fluid in it is more or less compressed than it is in its
natural state. Because Cavendish recognized the
need for two quantitative concepts, he introduced
another pair of opposing terms: a body is
"overcharged" or "undercharged" if it contains
more or less fluid than it does in its natural state.
Two overcharged bodies repel one another, as do
two undercharged bodies; an overcharged and an
undercharged body attract. Cavendish would refine
his theory; but already he had the theoretical basis
for his extraordinary course of electrical
experiments: that was the relationship between the
two quantitative concepts, pressure or degree of
electrification of a body and its charge.

To explain the attraction and repulsion of
electrified bodies. Cavendish introduced local
concentrations or deficiencies of electric fluid in a
space initially tilled with electric fluid of uniform
density. He then showed that upon his hypothesis,
two localized regions with more than their normal
quantity of fluid would "appear" to be mutually
repelled, one body receding from the other, just as
a body of greater density than water "tends to
descend in it." In Cavendish's first theory of
electricity, the only true (as opposed to apparent)
electrical force is the expansiv e force of the electric
fluid. Developing his electrical thoughts at the
same time that he carried out his researches on air,
Cavendish gave a mathematical investigation of
elastic fluids in general, and there he made
reference to air as frequently as to the electric
fluid, though electricity was his proper subject. 104
The paper "Thoughts," which was carefully
drafted in the early parts, ends with a troubling
thought: how far his hypothesis of an Watson-like
electric fluid diffused uniformly throughout all
bodies "will agree with experiment I am in doubt."
The mathematical investigation accompanying
"Thoughts" breaks off in mid sentence. Cavendish
changed theories.

Cavendish's new, published theory of 1771
was based again on an expansive electric fluid but
had a greater complexity of forces. He began with
an "hypothesis," which reads: "There is a
substance, which 1 call the electric fluid, the

particles of which repel each other and attract the
particles of all other matter with a force inversely as
some less power of the distance than the cube: the
particles of all other matter also, repel each other,
and attract those of the electric fluid, w ith a force
varying according to the same power of the
distance." 105 The hypothesis is close to Franklin's,
but there are important differences. By Cavendish's
but not franklin's, there is an electric force of
repulsion between the particles of ordinary matter,
which explains the repulsion of undercharged
bodies, the chief difficulty of Franklin's expla-
nation. Cavendish's hypothesis also differs from
Franklin's in that there is no mention of electric
atmospheres, as we pointed out in connection with
his earlier theory, and there is a statement about
the mathematical form of the law of force. These
differences facilitate the introduction of mathemat-
ical methods into electrical science; the forces
between particles of the two kinds of matter ex-
plain everything, and the forces enter as quanti-
fiable laws of force.

If the electric force varies with some power
of the distance less than the cube, the force acts
ov er sensible distances. Cavendish had grounds for
thinking that the force varies inversely as the
square of the distance, like gravitation; but the
known phenomena were not conclusive on this
point, and he had not completed his own experi-
ments to decide it. In any case, the theory con-
taining a range of possible laws of force and their
consequences had to come first. Just as Newton
had ultimately appealed to observations of the
planets, Cavendish appealed to observations on
electricity to decide between the alternative
possibilities for the distance dependency of the
real force.

In constructing his theory of the electric
force, Cavendish's point of departure (in both
senses) was the mathematical theory of air in
Newton's Principia. Newton derived the physical
properties of air by postulating a force between the
particles of air that varies as the inverse first (not
second, as in gravitation) power of the separation of

""Cavendish's first mathematical theory is reproduced in Sri.
Pap. l:.WK-l<)4.

'"■•Cavendish's paper was read at two meetings of the Royal
Society. 19 Dec. 1771 and 9 Jan. 1 772. "An Attempt to Explain Some
of the Principal Phaenomena of Electricity by Means of an Elastic
Fluid." /'7'61 (1771 ):.SK+-677; Sti. I'tif). 1:33-81, on 33.

Tools of the Trade

the particles. He derived from it Boyle's law
relating the volume and the density or pressure of
air, but this law was not as definitive as were
Kepler's laws of the solar system for Newton's law
of gravitation. Newton left it up to his followers to
diseuss if "elastic fluids do really consist of particles
so repelling each other." 106 Before his electrical
theory, Cavendish had already taken up Newton's
invitation. Newton, in his upwardly revised
derivation of the velocity of sound in air after
William Derham's experiments, implied that the
repulsion of air particles is inversely as the distance
from their surfaces, whereas experiment, Boyle's
law, requires it to be inversely as the distance from
their centers. To explain the higher velocity,
Newton also invoked the vapors in the air with
their different "tone," which to Cavendish was not
an explanation but an evasion. Newton's
derivations of Boyle's law and of the velocity of
sound both seemed right, and yet they were in
contradiction. About the mathematical law of force
of the particles of air. Cavendish was in
uncertainty. 1 " 7 In his preliminary thoughts on
electricity, Cavendish revisited this question, as we
have seen, and in the published paper in 1771 he
discussed it at length, at the end of his
development of electrical theory. It is what Newton
would have called a "scholium," an interesting
nonsequitur in a paper that is otherwise entirely
about electricity; the explanation for it is the
closeness of Cavendish's thinking about the two
subjects, electricity and air. It begins: "Sir Isaac
Newton supposes that air consists of particles
which repel each other with a force inversely as the
distance." 1 " 8 Cavendish enumerated a range of
laws of force for air, pointing out that each fails
either to give Boyle's law relating pressure and
density or to give the uniform distribution of the
particles of air. Cavendish concluded that the only
law that agrees with experiment is that of a force of
repulsion that varies inversely as the distance but
which terminates on the nearest particles, which.
Cavendish said, "seems not very likely." Newton's
law of force for air was regularly cited as a proven
truth, a consequence both of Newton's authority
and of the tendency of philosophy to follow where
mathematics leads. The result was that investigators
spoke of elastic fluids as though they were all of
one species in their mathematical description. By
contrast, Cavendish took up the question in

Newton's spirit, critically, and in the course of his
study he drew a mathematical distinction between
air and the electric fluid. Just as his experimental
discrimination between several elastic, factitious
airs helped discredit the notion that there was only
one true, permanent air, his mathematical
investigations showed that there were elastic fluids
in nature that must be represented by different
mathematical laws.

In his published theory of electricity,
Cavendish made some changes in terminology. He
spoke of "positive"' and "negative" electrification
or "degree" of electrification instead of his earlier,
more graphic "compression," but the concept was
the same; namely, pressure. He introduced a term
he was then using in his chemistry, "saturation," to
describe what he had called the normal or natural
state; in chemistry it meant that the affinities of
particles were rendered inactive in a chemical
union, and in electricity it meant that attractiv e and
repulsive forces were equal and no net electrical
activity was manifest. Cavendish spoke of electric
and common matter as "contrary" matters, behaving
in some respects like acids and alkalies or like
factitious air and the bodies absorbing it; the main
difference in these comparisons is that the
electrical fluid is free to move inside conducting
bodies and is prevented from running out of those
bodies by the non-conducting air outside the bodies.
Any departure from the saturated state causes a body
to be "overcharged" or "undercharged," as before.

Cavendish presented his electrical theory in
the form of Euclidean demonstration. This
rigorously deductive model had been extended
from the geometry of the ancients to the sciences;
in antiquity by Archimedes, and in recent times by
(ialileo and Newton using modern mathematics.
For British scientific authors in the eighteenth
century, Newton's Principia was the standard of
scientific exposition, and it was naturally adopted
by Cavendish, who developed his electrical theory
by definitions, propositions, lemmas, corollaries,
problems, cases, and remarks. With these cate-
gories, he analyzed the electrical content of mathe-
matically treatable bodies such as spheres, discs.

l06 Newton, Mathematical Principles 1:302.
" l7 IIcnrv Cavendish, "Concerning Waves," Cavendish Ms-.
VKb), 23:5. '

'""Cavendish. "An Attempt," 65.

178

Cavendish

and parallel plates, and he considered complicated
systems of bodies in electrical equilibrium by
connecting them with "canals," or wire-like
threads of matter through which the electric fluid
can freely move. Cavendish's theory of the electric-
fluid was an original essay in the difficult and still
rudimentary science of fluid mechanics. Caven-
dish, we note, also worked on standard problems of
fluid mechanics. IIW The foundation of Cavendish's
electrical theory was again his mathematical
education at Cambridge with its emphasis on

PLA TE IV. Lcyden Jar. Cavendish analyzes the the phenomena of the
Leyden jar using this diagram; that the "jar" is not in the shape of ajar
makes no difference to its working. ACGM stands for a plate of glass
seen edgeways, on either side of which are plates of conducting matter,
such as metal foil. The dotted lines indicate the possible penetration of
the electric fluid into the glass from the conducting plates. To charge
the Leyden jar, one conducting plate is electrified, the other grounded.
If a canal (wire) NRS is connected to the two conducting plates, the
redundant electric fluid passes from one to the other, "and if in its way
it passes through the body of any animal, it will by the rapidity of its
motion produced in it that sensation called a shock." "An Attempt to
Explain Some of the Principal Phaenomena of Electricity, by Means of
.in Elastic fluid." Philosophical 'Transactions 61 (1771): 623.

Newton's mathematics and mechanics. His theory-
was the single most impressive use of this
education in the second half of the eighteenth
century in Britain.

Cavendish's published paper of 1771 had
two parts, the first theoretical, the second an
application of the theory to experiments done by
others. Civen Cavendish's experimental skill and
interest, it might seem odd that he used only
experiments by others to confirm his theory. There
were two reasons why he proceeded this way. First,
the experiments he cited would be well known to
his readers, being the work of Canton, Franklin,
and other leading experimenters; they were the
experiments on attraction, induction, the Leyden
jar, and other phenomena that largely defined the
experimental field. The other reason was that at
the time his paper was read to the Royal Society, at
the end of 1771, he had just begun his own
experiments on a new class of phenomena
predicted by his theory. Wanting to present these
in completeness, he mentioned in his paper that he
intended to follow this one with a publication of
his own experiments. He also mentioned that
these earliest experiments of his pointed to the
inverse square law as the law of the electric force,
which he also had not yet confirmed by
experiments of his own. The paper of 1771 was
only the beginning.

We have reserv ed to the end of our discus-
sion of Cavendish's electrical theory our thoughts
about its origins. This seemed to us the right order,
since we wanted first to show how extensivelv his
electrical theory was connected with his con-

""The indispensable "canals" communicating (incompressible,
he assumed here) electric fluid were derivative of the canals of fluid
mechanics. Cavendish used "canals" in his work, for example on
wave motion: "Concerning Waves." Cavendish Mss \ Kb), 23.

Tools of the Trade

170

temporary' work in dynamics, heat, and chemistry 1 .
To this indigenous source we should recall that
electricity was of particular interest to Cavendish's
father. As for Cavendish's immediate incentive, we
have little to go on, especially since in the decade
or so before Cavendish's publication, relatively
little was done on the subject of electricity in
Britain. The fundamental researches of Watson,
Franklin, and Canton belonged to an earlier time,
the 1 740s and 1 75()s. The Philosophical Transactions
for the 1760s were particularly barren, and in the
years immediately preceding Cavendish's paper,
the only electrical publications in the journal were
one by Giambatista Beccaria and several by
Priestley on experiments originating in his History
of Electricity. Cavendish's paper was the only one on
electricity in the journal for 1771. New books in
English on electricity in the years before 1771 were
almost non-existent, and with two exceptions none
was influential. One exception was Priestley's
history in 1767, the full title of which is History and
Present State of Electricity with Original Experiments.
This book interested Cavendish not for the
"history" but for the "present state" of the
electrical research, of which Priestley gave a full
account. Cavendish made six references to
Priestley's book in his 1771 paper, and these six
constitute a majority of his references. The book
stimulated Cavendish for the wealth of experi-
ments it brought together, though it definitely did
not for what it had to say about the mathematical
side of the subject. The deficiency was not
Priestley's fault (with one exception, discussed
below), since electricity had hardly begun to
become mathematical. Priestley, who had no
training in mathematics, could recommend elec-
trical research because it required no "great stock"
of knowledge, and "raw adventurers" like himself
could make first-class discoveries. Priestley listed
mathematics as one of the supplementary fields an
electrician would be wise to cultivate, but he
foresaw experiments as the expanding direction.
With regard to mathematics, the one glaring
weakness of the History was its account of F. U. T.
Aepinus's theory, the first and only major attempt
to make a mathematical theory of electricity. 110
Priestley dismissed Aepinus's theory (but not his
experiments, which he admired) because he
thought, incorrectly, that it was based on an
incorrect law of electric force, one which led to

Boyle's law for air and not the facts of electricity,
and that accordingly electricians would save
themselves a "good deal of time and trouble" by
not bothering with it. 111 One of Newton's legacies
to science was his optical "queries," and Priestley
offered his own in electricity, including this: by
what law do the particles of the electric fluid repel
one another? 112 It is not surprising that in the 1760s
Priestley should ask this question but it is
surprising that he should give a correct answer to it.
From Franklin's observation that cork balls do not
separate inside an electrified cup, Priestley inferred
that the electric force varies inversely as the square
of the distance. Cavendish did not mention this
observation by Priestley, but the law of electric
force was basic to his mathematical theory of
electricity, and his own famous proof of the
inverse-square law, his hollow-globe experiment,
was an elaboration of the electrified cup. The other
book that appeared right before Cavendish's paper
was the fourth edition of Franklin's Experiments and
Observations on Electricity. Published in 1769, a
point halfway between Priestley's History and
Cavendish's paper, this edition of Franklin was
cited by Cavendish, and it may have contributed to
his change of theories. Here Franklin included a
letter to Hbene/er kinncrsely in which he spoke of
the repulsion of negatively electrified bodies as a
first principle. Franklin, who had rejected a
repulsive force in the past, now was persuaded of
it, and in its defense he recalled Newton's assertion
of repelling forces throughout nature. This edition
of Franklin could not be the cause of Cavendish's
researches in electricity, but it could have helped
reshape them.

The opening paragraph of Cavendish's
paper refers to Aepinus's Tentamen theoriae elec-
tricitatis et magnetismi. Only after he first wrote his
paper, he said, did he learn that Aepinus had used
more or less the same hypothesis and had arrived at
more or less the same results. Cavendish noted,
correctly, that he had "carried the theory much
farther" and "in a more accurate manner," and
therefore he was going ahead with his own paper.

II0 R. W. Home, cd, Aepinus's Essay on the Theory of Elettririty rind
Magnetism, trans. P. J. Connor (Princeton: Princeton University Press,
1979), 136.

"'Priestley, History of Electricity, 463.

"-Ibid. 488.

180

Cavendish

That was all Cavendish said about Aepinus. In
recent times. Cavendish's remark has been
subjeeted to historical scrutiny. A case has been
made that Cavendish had his own copy of Aepinus
in 1766, five and a half years before his paper on
electrical theory was read to the Royal Society, and
if that is so. Cavendish's assertion that he came
across Aepinus only after completing his paper is
bewildering. We know that his paper was not yet
written in 1766. The argument for making 1766 the
year of Cavendish's encounter with Aepinus
depends upon a series of assumptions all having to
do with Priestley. We need to explain how
Priestley, Cavendish, and Aepinus came together,
with Canton the middleman.

Aepinus, a leading member of the St.
Petersburg Academy, published the Tentatnen in
1759. On 23 June of an unspecified year. Caven-
dish wrote to John Canton to say that Canton need
not ask Priestley for the book since he found a
copy in a London bookstore." 3 The letter has been
attributed to the year 1766 on the basis of a series
of assumptions: that Priestley did not own the
book; that Canton lent him his copy for his History
of Electricity; that Priestley would not have kept the
borrowed book after finishing his book in 1767; and
that Priestley's interest had turned to other matters
and he would not borrow Aepinus's book again. 114
All of the assumptions have a degree of plausibility,
and they can all be reasonably doubted too. There-
was nothing, for example, to prev ent Priestley from
borrowing Canton's copy of the Tentamen again, if
that is what had happened before. Priestley was
still doing electrical research and, in fact, was the
principal contributor on the to the Philosophical
Transactions to 1770. As late as 1773 he was
planning to write a continuation of his History of
Electricity, and he consulted books on electricity for
his revisions of the History in 1769 and 1 775. 1 15

The Tentamen is the only book Cavendish is
known to have tried to borrow from someone.
Given his shyness, he would not have made the
request lightly, and once having gone to this
considerable trouble to locate it, he would not have
acquired it for the purpose of gathering dust on his
shelf for five and a half years before opening it,
while in the meantime he himself was working
hard on precisely the same subject, the
mathematical principles of electricity. Cavendish
bought books not to bind in leather for display but

to read. On the basis of the fragmentary corre-
spondence that has survived. Cavendish's letter
informing Canton that he had found a copy of the
Tentamen could have been written in any of the
years between 1766 and 1771, and all things
considered, especially from what we know of
Cavendish's habits, we think that in all likelihood it
was 1771, a few months before his paper was read to
the Royal Society. In any case, that would have been
about the time he first looked in Aepinus's book.

The main interest of the episode of Aepinus's book
lies not in anything it tells us about Cavendish but
in what it reveals about electrical work in Britain at
the time. A related interest is in what it reveals
about the communication of science at the time. In
1762, three years after Aepinus's Tentamen was
published, a large shipment of publications from
the St. Petersburg Academy was received in
London. Thomas Birch, who was then secretary of
the Royal Society, was sent a letter in late
September 1762 alerting him to the shipment and
also giving him a list of twenty-seven persons to
receive Aepinus's publications. Canton is not on
the list, nor is Priestley, nor, of course, either of the
Cavendishes, but many friends of the Cavendishes
are on it: Heberden, Watson, Macclesfield, Knight,
Wray, and Willoughby, to name several. The
parcels were addressed to the Royal Society, the
British Museum, Cambridge, Oxford, and
individuals. 1 "' We know that the Royal Society
received its parcel in early November and that it
contained the Tentamen among other publications
by Aepinus, and we assume others on the list also
received the Tentamen. The list contains some
excellent experimentalists, notably Watson, but
there is no one on it who could develop a
mathematical theory of electricity or perhaps even
follow one. Just as there would be no audience in
Britain for Cavendish's mathematical theory in
1 77 K there was none in 1762 for Aepinus's. It

"'Henry Cavendish to John Canton. 23 June. Canton Papers.
Royal Society, correspondence, vol 2.

II4 R. W. Home. "Aepinus and the British Electricians: The
I )issemination of a Scientific Theory," Isis 63 (1972): 190-204.

"'Joseph Priestley to John Canton. 24 May 1768; Joseph
Priestley to Alesssandro Volta, 10 Nov. 1773. in A Scientific
Autobiography of Joseph Priestley (1733-1804). ed. R. K. Schofield
(Cambridge, Mass.: MIT. Press, 19661,68 69. 144.

'"■Daniel Dumaresque to Thomas Birch, 25 Sep. 1762, BL Add
Mss 4304. p. 79.

Copyitghied maieiial

Tools of the Trade

181

is entirely conceivable that Henry Cavendish
would have heard no discussion of Aepinus's work
in that direction, for there probably was none.
Priestley's revisions of his History of Electricity left
unchanged his discussion of Aepinus's mathematical
theory 11 7 suggesting that none of his electrical
colleagues recognized its error and corrected him.
By the time Cavendish read the Tentamen, he saw
that he had gone far beyond Aepinus, and that is
what he told the readers of the Philosophical
'Transactions in 1 77 1 .

Aepinus's electrical theory was first discussed
extensively in print in English only a half century

later, by John Robison. Because of its mathematical
nature, Robison said, Aepinus's theory was the first
to tread in Newton's footsteps, and in this respect
so it was. 11 * Robison was a great admirer of
Cavendish's electrical theory, too. His praise, of
course, came too late to make any difference to
Cavendish, Aepinus, or the science of electricity.

'"Personal communication from Robert E. Schofield.
""John Robison. .1 .System of Mrrhamral Philosophy, 4 vols. ed.
with notes by D. Brewster (Edinburgh, 1822)4:109.

Copyighied mawi

CHAPTER 5

Electricity

Electricity better than any other subject allowed
Cavendish to make use of all of his skills as an
improver of instruments, a constructor of mathe-
matical theories, and a maker of experiments. In
the last chapter we discussed the electrical theory
he published; in this we discuss the electrical
experiments that followed from it.

Cavendish's experimental precautions were
legion. To give one example: he calculated the
inductive influence on his apparatus of the
experimental room itself, which he imagined to be
a sphere sixteen feet in diameter, "about its real
size." 1 (The precaution is analogous to that of the
astronomer who considers the disturbing gravita-
tional influence on his instruments by nearby
mountains; it may not be a coincidence that
Cavendish was working on the attraction of
mountains for the Royal Society at the same.)
There were very few electrical instruments, and
Cavendish, as usual, did not invent new ones but
adapted the best then in use, making endless
comparisons of electrometers for measuring charge,
Henley's, Lane's, and his own variants. His last
experiments were on electrical conduction, for
which there did not yet exist a measuring
instrument, a limitation he overcame by using his
body as an ingenious kind of galvanometer. His
great battery of Leyden jars was similar to
Priestley's, the first large battery. 2

Capacity

When in his published paper of 1771
Cavendish supported his electrical theory with
well-known experiments by others, he had just
begun to do experiments of his own, of a new kind.
The trials of the quantitative predictions of his
theory turned out to be a work of several years.

Cavendish never delivered the experimental
paper he promised in 1771, not because of
disappointed hopes but because of unexpected
riches. His theory pointed to a vast region of new

electrical facts, which, given his caution and his
curiosity, he had to pursue to the last experiment.
In this respect his theory was a success, which in a
contrary way deflected him from publishing his
experiments soon or, as it turned out, ever.

From the numbering of his experiments
and other indications, we know that Cavendish's
next paper would have given an experimental
proof of the mathematical law of the electric force
followed by the entirely new consequences he
drew from this law together with the rest of the
theory. Here Cavendish followed Newton, who
deduced from the facts of planetary motions the
inverse-square law of gravitation. Then, just as
from the law of gravitation, Newton derived other
planetary phenomena, from the law of electrical
force Cavendish derived other phenomena of
electricity. From his first experiments on electrical
capacities, Cavendish anticipated that the electric
force obeys the inverse-square law, but he needed
an independent proof; two years passed before he
came up with his famous hollow-globe experiment. 3

Several attempts had been made to deter-
mine directly the law of electric force by experi-
ment, for example, by Stephen Gray, Cromwell
Mortimer, Daniel Bernoulli, and John Robinson.
The latter two concluded that the law was the
same as that of gravitation. There had also been an
indirect inference of the law of electric force,
Joseph Priestley's, as we have noted; according to a
well-known theorem of the Principia, there is no
force in the interior of a gravitating shell if the force

'Henry Cavendish, The Scientific Papers of the Honourable Henry
Cavendish, vol. 1: The Electrical Researches, ed. J. C. Maxwell, rev.
J. [.armor (Cambridge: Cambridge University Press, 1921), 169.

'William I). Hackmann. Electricity from Class: The History of the
Frictional Electrical Machine 1600-1850 (Alphcn aan den Rijn: Sijtoff
& Noordhoff, 1978), 99-100.

'The discussion in this chapter is drawn from Russell
McCormmach, "The Electrical Researches of Henry- Cavendish,"
Ph.D. diss.. Case Institute of Technology, 1967, especially chapter 4,
"Cavendish's Electrical Experiments," and chapter .S, "Conclusion."
322-197.

Cavendish

of gravitation obeys the inverse-square law. Other
electricians gave different explanations of the
electrified cup; Canton told Priestley that it
contained "no mystery." 4 Only Cavendish, it
seems, followed up Priestley's reasoning.

Cavendish demonstrated mathematically
that if the intensity of the electric force falls off as
the inverse-square of the distance from the electric
source, the redundant electric fluid on an
electrified sphere lies entirely on its outer surface.
He made two conducting globes of slightly
different sizes, placing one inside the other and
connecting them electrically. I'pon electrifying the
outer globe, he found that the inner globe was not
electrified, in agreement with the inverse-square
law. The rough instrument he used for detecting
any electricity on the inner globe — a simple pair of
pith balls suspended by linen threads — he made
into an instrument of relatively high precision by
his method. By reducing the chatge of the Leyden
jar to one sixtieth of its original strength and
applying it to the globe, he found that the pith
balls barely separated. With that measure of the
sensitivity of his apparatus, he knew that the
quantity of redundant electricity communicated
from the outer globe to the inner globe was less
that one-sixtieth part of the redundant electricity,
and he concluded that there was no reason to
believe that any redundant electricity was
communicated to the inner globe. He expressed
this result in a more meaningful form: the electric-
force varies inversely as some power of the distance

PLAIT V. Hollow-Globe Apparatus. With this apparatus Cavendish
demonstrates the law of the electric force. His drawing of it show s a
hinged wooden frame that when closed brings together two hemi-
spherical shells around but not touching an inner globe, w hich is 12.1
inches in diameter and suspended by a stick of glass. The hemi-
spheres and the inner globe are covered w ith metal foil, and a metal
connection is made between the two. When the frame is closed, the
hemispheres are electrified with a Leyden jar. Then the metal con-
nection is removed by a string from outside, and the frame is
opened. A pair of pith-balls shown in the drawing is brought against
the inner globe. Cavendish finds that the pith- balls do not separate,
showing that no electricity has been communicated to the inner
globe. By a theorem from Newton's Principia. Cavendish concludes
that the electrical force obeys the inverse-square law of the distance.
"Experimental Determination of the Law of Electric Force,"
Cavendish Mss I, 7(a); The Electrical Researches of the Honourable Henry
Cavendish, ed. J. C. Maxwell (Cambridge, 1879), 104.

between 2 + 1/50 and 2 - 1/50, from which he
concluded that there is "no reason to think that it
differs at all from the inverse duplicate ratio." 5
That is, if the inverse power of the distance of the
law of electric force were 2 + 1/50 or 2 - 1/50,
Cavendish would have detected a charge on the
inner globe. Cavendish repeated the experiment
replacing the globe within a globe by a paral-
lelpiped within a parallelpiped. Then, just as the
law of gravitation depends not only on the distance
between two bodies but also on the quantities of
matter in them. Cavendish did other experiments
to show that electricity has the same kind of law:
the electric force between two bodies depends also
on the quantities of redundant electric fluids in
them.' 1 A hundred years later, in the laboratory-
named after him at Cambridge, Cavendish's hollow-
globe experiment was repeated with refinements,
using an electrometer capable of detecting a charge
thousands of times smaller than Cavendish's, with
this result: the electric force varies inversely as
some power of the distance between 2 + 1/21600
and 2 - 1/21600. 7 We note that so compelling was
the example of the law of gravitation that
Cavendish did not consider the possibility that the
distance dependency of the electric force could be
anything but some inverse power of the distance. If

J John Canton to Joseph Priestley. 10 Jan. 1767, Canton Papers.
Royal Society. Correspondence 2.

''Henry Cavendish. "Experimental Determination of the Law of
Electric Force." Set. Pap. 1:124.

'■Henry Cavendish. "Whether the Force With Which Two
Bodies Repel Is as the Square of the Redundant Fluid, Fried by
Straw Electrometers," Sci. Pap. 1:189-93.

'The experiment was done by Donald MacAlister in 1877 and
1878 under Maxwell's direction. James Clerk Maxwell, "On the
Unpublished Electrical Papers of the Hon. Henry Cavendish," Proe.
Camh. Phil. Soc. 3 (1877): 86-89, on 87.

Electricity

the null result of his hollow-globe experiment was
compatible with a different kind of force,
Cavendish did not regard it as a physically
significant alternative.* Cavendish did not publish
his indirect experimental determination of the
inverse-square force; in the 1780s, Charles
Augustin Coulomb established the law directly
with a torsion balance, and with Coulomb's
publication the law went into history.

Cavendish's plan for the published work
was to follow the proof of the inverse-square law
with experiments that confirmed his theory as a
whole. The experiments were carried out on the
charges of bodies of various sizes and shapes, con-
nected by slender wires, the material embodiment
of the canals of incompressible fluid of his theory.
These were experiments on what came to be
called the electrical "capacities" of bodies, a new
activity in electrical science owing entirely to his
theory. His method depended upon his leading,
original idea in electrical theory, the "degree of
electrification," which we can think of as equivalent
to our electrical potential. Electrically connected
bodies of various shapes and sizes carried different
charges at the same degree of electrification; the
ratio of these charges was therefore physically
meaningful and. Cavendish showed, measurable.
Repeating his approach in chemistry, to compare
the electrical capacities of bodies, he introduced
standard measures, here a conducting globe of 12.1
inch diameter, the same globe that he used in the
hollow-globe experiment, and "trial plates," which
were pairs of rectangular tin sheets that could be
slid across one another to vary the area of the
rectangle. Having shown that the charges of similar
bodies are proportional to their linear dimensions,
he could express his experimental results simply;
his preferred way was to state the charge of a body
as the charge of a globe of the same capacity at the
same degree of electrification, as "globular inches"
or "inches of electricity." By his extraordinarily
careful technique, he obtained highly precise
results for his capacities with the use of a simple
pith-ball electrometer. For example, he found the
ratio of the capacity of a circular disc to that of a
sphere of the same diameter to be 1/1.57; today the
theoretically calculated value is 1/1.570. . . . 9

The "work," the electrical publication in
progress, had another "Part," which was about
experiments on the charges of plates of glass and

185

other non-conductors coated in the manner of
Leyden jars. For these experiments Cavendish
again introduced trial plates, in this case plates that
were themselves simple Leyden jars, plane glass
plates with circular coatings of foil. The thickness
of the glass he determined accurately with a Bird
dividing engine.

This part of Cavendish's work has a
decidedly unfinished quality to it. In fact, Leyden
jars caused such difficulties for the theory that early
on he feared that the "reader" might suspect that
there was "some error in the theory." 10 He convinced
himself that there was not, but it took a great many
experiments and all his theoretical ingenuity.

In a qualitative way Cavendish's theory
explained Leyden jars perfectly well, as he had
shown in his published paper of 1771, but now
Cavendish was doing quantitative electricity. The
Leyden jar nearly ended his career as a
mathematical electrician when he found that the
measured charge of a glass Leyden jar was eight
times greater than the charge predicted by his
theory, a discrepancy which could not be written
off as experimental error. "This is what I did not
expect before I made the experiment," he said in
the manner of understatement, and he then
proposed an explanation of why the glass of the
Leyden jar acted as if it were eight times thinner
than it actually was. Glass, he reasoned, has an
electrical structure according to which non-
conducting and conducting parts are arranged in
alternating layers, the thickness of any one
conducting layer of glass being "infinitely small." 11
For the explanation to work, the total thickness of
the non-conducting parts has to be one eighth the
thickness of the conducting parts. Lest the
explanation seem entirely ad hoc, Cavendish made
an "analogy between this and the power by which

"Laplace K avc the first proof that for there to be no force inside
a uniform hollow nlobc. the only function of the distance it can have
is the inverse square, as noted by Maxwell in the Electrical Papers of
the Honourable Henry Cavendish (London, 1879), All. Laplace's proof
still does not rule out other possible forces consistent w ith Cavendish's
experiment: the point is discussed in Jon Dorling, "Henry
Cavendish's Deduction of the Electrostatic Inverse Square Law from
the Result of a Single Experiment," .Studies in the History una 1
Philosophy of Science 4 (1974): 327-48, on 335-36, 341-42.

''R. J. Stephenson, " The Electrical Researches of the I [on. I lenry
Cavendish, F.R.S.," The American Physics Teacher b (1938): 55-58. on 56.

"»I lenrv Cavendish, "Experiments on Coated Plates," Set. Pap.
1:151-88, on 180.

"Ibid., 176.

186

a particle of light is alternately attracted and
repelled many times in its approach towards the
surface of any refracting or reflecting medium." He
directed the reader to John Michell's explanation
of Newton's so-called fits of easy reflection and
transmission of light, 1 - according to which each
particle of a refractive or reflecting medium is
surrounded by a great many equal intervals of at-
traction and repulsion, alternately succeeding one
another; a particle of light either enters the
medium or is deflected from it according to the
pattern of these forces. In Cavendish's analogy, the
particles of light are replaced by particles of the
electric fluid, which are bound or repelled by
forces of the particles of glass; where attractive and
repulsive forces coincide, the electric fluid is free
to move, constituting the infinitely thin conducting
layer. By this appeal to the general theory of matter
and forces that he accepted, Cavendish saved his
electrical theory. I le drew additional confidence in
his explanation from experiments on Lcyden jars
made of air instead of glass. The air jar did not give
an eightfold departure from the theory but agreed
with it, and since air does not have a fixed structure
like glass, the departure in the case of glass jars had
to arise from the glass and not from the theory. 1 - 5
Cavendish made a thorough study of the electrical
properties of glass, grinding the glass surfaces,
subjecting the glass to intense electrical forces, and
heating the glass of his Leyden jars in what was
essentially a continuation of his father's experi-
ments on the conductivity of hot glass.' 4 In trying
different kinds of glass and other non-conducting
substances. Cavendish made a fundamental dis-
covery, that of specific inductive capacities, which
would be rediscovered by Faraday in the next
century. He found that like the thermal properties
of different substances, the electrical properties of
different substances van. quantitatively and charac-
teristically. In both fields, heat and electricity,
Cavendish made this discovery by his quantitative-
experiments without any theoretical anticipation.
Within the context of experiments undertaken to
follow up the consequences of his electrical theory, his
experimental technique was in itself a tool of discovery.

Conduction

Before we return to the nature and fate of
Cavendish's "work," we will discuss the remainder of
his electrical experiments, which went well beyond

Cavendish

his theory of 1771. Phenomena of conduction were
only slightly represented among the "principal
phaenomena" of electricity of his paper of that
year. By 1773 he had changed his mind or at least
his direction; from then on all of his electrical
experiments were about conduction. He did a great
many experiments on the new subject, in the
course of which he revealed an ingenuity of
experimental method unsurpassed in any of his
other researches; he obtained results in very close
agreement with modern ones, but his account of
them remained in the form of rough notes, leaving
us partially in the dark about his motivations.
These experiments were, in his judgment, the
most inconclusive of his electrical experiments.

One reason why Cavendish took up
electrical conduction may have been his recent
study of the Leyden jar in terms of conducting and
non-conducting layers; moreover, it was generally
understood at the time that there was no sharp
division between conducting and non-conducting
substances. Here we should recall the setting of his
experiments on electricity, Great Marlborough
Street, where he lived with his father, who had
taken a great interest in electrical conduction in
glass and in other substances and even in the
vacuum. Henry Cavendish's work on conduction led
him in new directions, but it was clearly related to
his theoretical and experimental work in electricity
up to that point; his experiments on the conduction
of electricity closely paralleled the experiments he
had just concluded on electrical capacities.

Since in the 1770s current electricity was
still undiscovered, Cavendish studied conduction
using transient discharges of Leyden jars, and to
make the study accurate he made himself into his
own principal instrument of measurement. In other
kinds of experiments, Cavendish's primary sense
was variously sight, hearing, and occasionally smell
and taste, but in his experiments on electrical
conduction, it was touch or, to be more specific, an
electrically stimulated sensation in the skin of the
hands and in the internal nerves of the wrists and

'-'Michell's account was reported in Joseph Priestley's History
and Present State of Discoveries Relating to Vision, Light, ana" Colours
(London, 1772). 1:309-11.

"Cavendish, "Experiments on Coated Plates," 180.

l4 As reported by Benjamin Franklin, in Benjamin Franklin's
Experiments: A S'etr Edition of Franklin 's Experiments and Observations
on Electricity, ed. with historical introduction by I. B. Cohen
(Cambridge. Mass.: Harvard University Press, 1941), 363-64.

Electricity

187

elbows. His technique was to insert himself into
the electric circuit by holding a piece of metal in
each hand and touching one piece to the knob of a
Leyden jar and the other piece to one end of a
tube containing a conducting solution; the other
end of the conducting solution was connected by a
wire to the other side of the Leyden jar. For con-
taining his solutions, he used calibrated, glass tubes
about a yard long with wires inserted at each end as
electrodes. The resistance of a solution was varied
by sliding one of the wires to vary the effective
length of the solution. For the purpose of com-
paring one conducting solution with another, he
prepared a series of six equally charged Leyden
jars, which he then discharged alternately through
the two solutions (and himself), adjusting the wire
in one of the tubes until the shocks of the two
solutions were as nearly equal as he could judge. In
this way, with "truly marvelous" discrimination, he
obtained conductivities consistent with one another
and remarkably close to those obtained by later
experimenters with their instrument for the purpose,
invented forty years later, the galvanometer. 15

As we would expect, Cavendish explained
electrical conduction as he had electrical equilibrium,
by the fluid mechanics of the matter of electricity.
He attributed the shock he felt with his hands to
the combined effect of the quantity of electric-
matter discharged and its velocity. He experienced
the force of electricity in motion, the direct
electrical analogue of momentum, the product of
quantity of matter and velocity, the measure of the
force of ordinary matter in motion. In passing
through matter — wires, solutions, and flesh — the
electric fluid encountered "resistance," and as in
ordinary fluid mechanics. Cavendish assumed that
the resistance varied as some power of the velocity. 16
His experiments to determine that power yielded
the value 1 or values close to it; it has been pointed
out that if Cavendish's velocity is interpreted as
strength of current, or current per unit area, he
came upon what would later be known as Ohm's
law. 17 He arrived at a good many other results in
electrical conduction that others after him would
rediscover. (We make this observation about so
many of Cavendish's researches that it becomes
tiresome, but it is the truth all the same.)

By an oblique route, Cavendish revealed to
the public his understanding of electrical

conduction. Long before Luigi Calvani's work at
the end of the eighteenth century, animal
electricity had been recognized and studied, but its
identity with common electricity had yet to be
experimentally demonstrated. With Cavendish's
help, an electric fish called the "torpedo" was
shown to be capable of delivering stupefying
shocks with common electricity.

A number of species of fish belonging to
more than one genus are known to use electricity
as a weapon. The early experiences of our own
species with electricity may well have been by this
means, as Egyptian tombs portray fishermen with
the electric catfish of the Nile. The electric ray is
depicted in the ruins of Pompeii; Pliny wrote of it
that "from a considerable distance even, and if only
touched with the end of a spear or staff, this fish
has the property of benumbing even the most
vigorous arm, and of riveting the feet of the runner,
however swift he may be in the race." Its numbing
property gave rise to its Creek name, "narke," with
the same root at narcotic, and its Roman name,
"torpedo," from torporiftc. Biology subsequently
made distinctions between electrical fish, rays,
eels, and so on, naming them accord ingly. ls

Known in antiquity and in the Renaissance
as a magical fish, defying natural explanation, the
torpedo retained its occult aura even into the
eighteenth century but not beyond the
experiments of the 1770s. 1 '' In the decade before, it
had been suggested that the most formidable of
the electric fishes, a South American eel, the
FAectrophorns electricus, then called "Cymnotus,"
was indeed "electrical." This large, otherwise
almost blind, weak-swimming fish with small teeth
and no spines or scales was said to be able to kill
men and horses. The identification of the singular
power of the Cymnotus with electricity may be
why John Walsh, with Franklin's encouragement,
began to experiment on a nearby weaker electrical

'"■Maxwell's "Introduction," Electrical Researches of the Honourable
Henry Ctnendish, xxvii-lxvi, on Ivii-lviii.

" In treating the motion of bodies in resisting mediums, Newton
in the Prineipia assumed that the resistance is proportional to some
power of the velocity.

"Maxwell made this observation in Cavendish. Set. Pap. 1:25.

'"R. T. Cox, "Electric Fish," American Journal of Physics 11
(1943): 13-22, on 13-14.

'''Brian I'. Copcnhaver, "Natural Magic, 1 lermeticism, and
Occultism in Hark Modern Science," in Reappraisals of the Scientific
Revolution, eds. D. C. Linberg and R. S. Westman (Cambridge:
Cambridge University Press, 1990), 261-301, on 278-79.

Cavendish

» i /

> EOC » A

A »/ li

I'LATF. VI. Artificial Flcctric Fish. In Figure I, the broken lines stand for the paths of the eleetrie fluid, which passes from the electric rav. or tor-
pedo (solid line), in water. Figure I is Cavendish's handheld modified version of Timothy Lane's electrometer, made of brass and wood, indicat-
ing the distance a spark flies. Not show n is the pitch-ball electrometer used to estimate the strength of a charge. Resembling a stringed musical
instrument, the draw ing in Figure 3 is the artificial torpedo. Cut to the shape of the fish, a piece of wood 16 3/4 inches long and 10 ,V4 inches
w ide w ith a handle 40 inches long is fitted w ith a glass tube MNmn. A w ire passing through the tube is soldered at W to a strip of pew ter, w hich
represents the electric organs. The other side of the apparatus is fitted exactly the same way, w ith tube. w ire, and pew ter. With the exception of
the handle, the whole is wrapped with a sheet of sheep's skin leather. Figure 4 shows the apparatus immersed in a vessel of salt water. Through
the wires and the bod} of the artificial fish. Cavendish discharges portions of his great battery of 49 extremely thin-walled Lcyden jars. Figure 5
show s a device for testing if the shock of the artificial torpedo can pass through chain.

fish, the torpedo. Son of the governor of Fort
St. George at Madras, Walsh had served in the
East India Company, becoming paymaster to the
troops at Madras and then Clives private secretary
in India. Now a nabob and a Member of
Parliament, Walsh was well connected with men of
science: he was Nevil Maskelyne's first cousin, a
Fellow of the Royal Society, and a member of the
Royal Society Club, to whom he introduced two
Fskimos. J " Drawn to exotica in science as in life,
he was the sort of adventurous person whom
Cavendish regularly sought out. It was no doubt
through Walsh that Cavendish became involved
with the torpedo.

In 1 772 Walsh went on a torpedo hunt to La
Rochelle and the Isle of Re, France. From La
Rochelle he wrote to Franklin that he had found

the torpedo's effect to be "absolutely electrical." 21
As in earlier experiments with the Leyden jar, only
this time with the fish in place of the jar, several
persons joined hands and felt the shock together.
The back and breast of the fish have different
electricities like the sides of a Leyden jar, leading
Walsh to wonder if its effect could be exactly
imitated by one. He enlisted the anatomist John
I lunter to dissect a slablike specimen of a torpedo
a foot and a half long, a foot wide, and two inches
thick. Hunter was impressed by what he saw. Fach

^"Archibald Geikie. Annuls of the Royal Society Club (London:
Macmillan, 1°-17). 115-16, 121. "Walsh, John ." DNB 20:671-72.

JI John Walsh to Benjamin Franklin, 12 July 1772, quoted in
John Walsh, "Of the Electric Property of the Torpedo," W63 (1773):
461-KO, on 462.

Electricity

of the pair of electrical organs had about 470
prismatic columns, and each column was divided
by horizontal membranes, 150 to the inch, forming
tiny spaces filled with fluid.- 2 Hunter presented
the Royal Society with a pickled male and female
example of this wonderfully structured animal.

Serious doubts were raised about the electrical
nature of the torpedo, which could not produce a
spark or separate pith balls. One of the doubters
was the electrician William Henly, who (before
Cavendish) made an "artificial torpedo," of con-
ducting materials, which exhibited "no attraction or
repulsion of light bodies, no snap, no light, nor
indeed any sensation." Henly argued that the real
torpedo was in the same predicament as his artificial
torpedo, incapable of giving an "electrical sAoci." 23

Moreover, if the torpedo did have ordinary
electricity, it had to have a very great deal of it. The
Torpedo occidentalis (a larger electrical fish than
Walsh's torpedo) has been shown to deliver an
instantaneous maximum voltage of 220 volts and a
current of 60 amps.- 4 I low could a fish store all that
electricity, and how did it deliver it? Walsh turned
to Cavendish for the answers. Cavendish, he said,
was the "first to experience with artificial
electricity, that a shock could be received from a
charge which was unable to force a passage through
the least space of air." 25 Since Cavendish had
published nothing from his electrical experiments,
Walsh had got this information from him by
request sometime early in 1773. In 1774 Walsh
received the Copley Medal for his experiments on
the electrical nature of the fish, on the significance
of which the president of the Royal Society, John
Pringle, had this to say: "between lightning itself and
the Leyden Phial there is no specific difference,
nay scarcely a variety, as far as is known, why then
should we unnecessarily multiply species and
suppose the torpedo provided with one different
from that which is everywhere else to be found?" 26

Cavendish went on to construct an artificial
torpedo based on the anatomy and electricity of the
fish, and in 1776 he published a paper on it. 27 A
main objection to the idea that the torpedo pos-
sesses electricity was that its tremendous shock is
delivered underwater where the electric fluid has
easier channels than through the victim's (or the
observer's) body. That criticism was based on the
commonly held but incorrect view that all of the

189

electric fluid flows along the "shortest and
readiest" path. The paths it actually takes depend
on the relative resistances of all of the paths
available to it. The reason, Cavendish explained,
why a person holding a wire with both hands, and
thereby forming a parallel circuit with the wire,
does not feel a shock when a discharge is sent
along the wire is that the resistance of the body is
so much greater than that of the wire that only an
insensible fraction of the discharge passes through
the body. To explain how a fish could throw a great
shock and yet not produce a spark, Cavendish
noted that the length of spark from a battery of
Leyden jars varies inversely as the number of jars
in the battery. He believed that the electric organs
of the torpedo are equivalent to a great number of
Leyden jars connected like a battery: these living
jars are weakly electrified, but because of their
great number, they can store a large quantity of
electricity. Cavendish answered another common
objection with this observation: the discharge of
the torpedo is completed so quickly that a pair of
pith balls in contact with the animal does not have
time to separate. To prove the correctness of his
explanations, Cavendish built his artificial torpedos.
His first one was cut out of wood in the shape of
the fish, but it did not conduct as well as
Cavendish thought the real fish did; he built a
second one by pressing together shaped pieces of
thick leather like the "soles of shoes" to represent
the body, and attaching thin plates of pewter to
each side to imitate the electric organs. With glass-
insulated wires he connected the pewter plates to a
battery, and he encased the whole in sheep's skin
soaked in salt solution, the stand-in for the skin of

''William Henly to William Canton. 14 Mar. 1775, Canton
Papers, Royal Society, Correspondence 2:104.

- 4 R. T. Cox, "Electric Fish," American Journal of Physics 11
(1943): B-22, on 19. In one plate among his notes on the torpedo
experiments. Cavendish referred to an artificial Cymnotus.
Cavendish. Set. Pnp 1: 304. This fish is an "electric eel" (though not
truly an eel but related to the carp and catfish), and it is the most
formidable of all electric fishes. Its electrical organs extend to the
length of its tail, four-fifths of its body, and so its anatomy in this
respect is entirely different from that of the torpedo.

"Walsh, "Torpedo," 47b.

26 John Pringle, A Discourse on the Torpedo Delivered tit the
Anniversary Meeting of the Royal Society, November 30, 1774 (London.
1775). Quoted in Dorothea Walcy Singer, "Sir John Pringle and His
Circle.— Part III," Annuls ofSciemeb (1950): 248-61. on 251.

-'Henry Cavendish. "An Account of Some Attempts to Imitate
the Effects of the Torpedo by Electricity," PT 66 (1776): 196-225; in
Sci. PapX: 194-210.

190

Cavendish

the torpedo. Discharging different numbers of
Leyden jars through the artificial torpedo and
placing his hands on or near it, he found that the
sensations agreed w ith descriptions of the shock of
the real torpedo. W ith the artificial torpedo out of
water, the shock was:

very slight in tinkers.

only in hands, there seemed to be something wrong,
brisk in elbows,
briskish in elbows.
I'nder water it was:
just sensible in hands,
stronger.

pretty strong Do. 2 "

So that others could experience his artificial
torpedo. Cavendish invited into his laboratory a
number of interested persons: the torpedo
anatomist Hunter, of course; Lane, whose
electrometer Cavendish was using; Nairne, whose
battery and coated glass plates he was using;
Priestley, who was in London on a visit; and
Thomas Ronaync.-"' The latter, a skeptic, had said
of Walsh's electrical hypothesis of the torpedo that
he would have to "give up his reason" to believe-
that the tissues of the fish could accumulate
enough electricity to deliver a shock; he left
Cavendish's laboratory a believer, we presume,
since Cavendish recorded in his notes of the visit
"Mr Ronaync felt a small shock." 30 For reason was
with Cavendish, who pointed out that the battery
of the real fish was superior to his, stupendous as
his was for the time, seven rows of seven thin-
walled jars each, equivalent in capacity in his units
to a sphere 321,000 inches or 26,750 feet across.' 1
From Hunter's observations Cavendish calculated
that the torpedo had nearly fourteen times the
electrical capacity of ev en this battery. I Ie
concluded that "there seems nothing in the
phenomena of the torpedo at all incompatible with
electricity." 5 - Cavendish's was not to be the last
word on this question, since the discovery of the
Voltaic battery provided a better analog of the
electric organs of fishes than the Leyden-jar
battery. Davy, Faraday, and others did the
definitive researches on the electrical character of
the several kinds of electrical fish." Although
Cavendish thought that it was likely that the
electric fish contained something "analogous" to
the Leyden-jar battery, he also considered that
there might be no such thing, and in envisioning
the possibility that the electric fluid is not stored

but gradually transferred by a small "force"
through the substance and over the surface of the
body of the fish, he anticipated (it has been
pointed out) the Voltaic battery and the associated
fundamental concept of electromotive force.' 4

Cavendish came to his conclusions about
the torpedo entirely from scientific reasoning; for
he certainly had never seen or touched a live
torpedo. The significance of his paper on the
subject was, above all, as a highly abbreviated
treatise on the principles of electricity and a primer
on laboratory technique. The main ideas and
methods were all there, introduced by Cavendish
as needed to support his arguments. This applica-
tion, the torpedo, was, in fact, ideal for laying out
the science. The question of the nature of the
torpedo was tantamount to a series of related,
fundamental questions: what is electricity, how is it
produced, how is it stored, how is it conducted, how
is it manifested, and how is it conceived, mani-
pulated, and measured?

After his paper on the torpedo, Cavendish
continued to experiment on conduction. I "sing a
given salt solution as a standard measure, he
determined the conductivities of solutions of fixed
air, acids, and salts in water. Maxwell noticed this
striking fact: the quantity of each acid and salt
Cavendish used was proportional to its modern
chemical equivalent weight. The explanation lies
in Cavendish's use of standards and in coincidence.
Cavendish expressed his equivalents in terms of
his standard, 1000 grains of marble: his equivalent
weights of various substances yielded the same
volume of fixed air as did 1000 grains of marble. If
Cavendish had taken as his standard 100
pennyweights of marble, then since the modern
equivalent weight of marble happens to be 100, the
equivalents of other substances, as we list them.

J "IIcnry Cavendish, "Experiments with the Artificial Torpedo,"
Cavendish Mss l:20(a), in Electrical Researches of the Honourable Henry
Cavendish, 310-20. on 312-13.

-"'The guests are named in Cavendish's laboratory notes for 27
Ma\ 177.S. Ibid.. 313.

"'Ibid. Letter from William Henly, 21 May 1775, Canton Papers,
Royal Society; quoted in Electrical Researches of the Honourable Henry
Cavendish, xxxvii.

"Maxwell's note: Electrical Researches of the Honourable Henry
Cavendish, 299.

'-Cavendish, " Torpedo." 213.

"Maxwell's note: Electrical Researches of the Honourable Hemy
Cavendish, 435-37.

"Cox, "Electric Fish," 21-22.

Copyrighted maieiial

Electricity

191

would be exactly as Cavendish listed them. 35

In his experiments on conductivities,
Cavendish was painstaking as always. Maxwell
made extensive comparisons between Cavendish's
values and the values obtained with electrical
instruments of precision a hundred years later.
Typical of his wonder at Cavendish's accuracy is his
opinion on Cavendish's comparison of the
resistances of iron wire and salt water: "The
coincidence with the best modern measurements is
remarkable.""' Cavendish carried out experiments
on the conductivity of solutions through early 1777.
Then, after a lapse of four years, in 1781 he
returned briefly to the subject and then not again.
Cavendish had at last, it seems, run out of original
ideas he wanted to try in electricity, but by then he
was deeply immersed in his experiments on air.

The Work

We close this account of Cavendish's elec-
trical experiments with a discussion of the total
"work," the book he intended to publish and did
not, and of the response to what he did publish.
When his paper on electrical theory was read to the
Royal Society in 1771, Cavendish was immediately
recognized as an authority in electricity. In the
following year he was appointed to an ongoing
committee of the Royal Society to protect the
powder magazines at Purfleet from destruction by
lightning. The government made the request, and
the Royal Society responded by volunteering its
best local electricians, Watson, Franklin, Wilson,
and, its most recent arrival, Cavendish." In 1773
this committee paid a visit to Purfleet to confirm
that the lightning conductors were erected
according to their instructions. 58 This work of
oversight was ongoing, and Cavendish was always a
part of it, though in his own research he was no
longer working in electricity. 39 Many years later
Cavendish and Charles Blagdcn were appointed a
committee to reexamine the state of the con-
ductors at Purfleet, 40 and in 1801 Cavendish was
appointed to a committee with the related
assignment of determining the proper floor
covering to reduce frictional electricity at powder
magazines and works. 41

The remarkable fact about the response to
Cavendish's electrical theory is that it was almost
non-existent. Writers on electricity after 1771
showed no awareness of the need for two indepen-

dent quantities in electrical theory, and there is no
evidence that Cavendish's publication stimulated
an interest in mathematical electricity, nor that it
led to any electrical experiments but his own. The
fate of his published electrical theory hardly
differed from that of his manuscripts: both were
noticed only after most of his results had been
rediscovered by others. His theory of electricity
was not entirely unknown — it was published, after
all — but it remained remote to, and little under-
stood by, subsequent electrical researchers.

In 1812, the year of Simon Denis Poisson's
great mathematical theory of electricity, and forty
years after Cavendish's theory, Thomas Thomson
wrote in his History of the Royal Society:

The most rigid and satisfactory' explanation of the
phenomena of electricity, which has hitherto
appeared in any language, is contained in a very
long, but most masterly paper of Mr. Cavendish,
published in the Philosophical Transactions for
1771. It is very remarkable, and to me an
unaccountable circumstance, that notwithstanding
the great number of treatises on electricity which
have appeared since the publication of this paper,
which is, beyond dispute, the most important
treatise on the subject that has ever been
published, no one, so far as I recollect, has ever
taken the least notice of Mr. Cavendish's labours,
far less given a detailed account of his theory.
Whether this be owing to the mathematical dress
in which Mr. Cavendish was obliged to clothe his
theory, or to the popular and elementary nature of

"Maxwell, in Cavendish. .SW. Pap. 1:28. 321.
"Mawell's note: Electrical Researches of the Honourable Henry
Cavendish, 444.

"Royal Society, Minutes of Council 6:146 (26 Ann- 1772). This
was the second committee on the conductors; the first, in 1769, was
without Cavendish, who had not yet published on electricity. The
second committee, with Cavendish, gave a report and recommenda-
tions. Wilson dissented from the opinion of the report and did not
sign it. Also on the committee was the clerk of the Royal Society,
John Robertson, who was a skilled scientific investigator but had
done no published work in electricity.

'"Royal Society, Minutes of Council 6:195-96 (22 Nov. 1773).

v 'ln 1777 there was a third committee with an almost entirely new
membership, with the exception of Cavendish. On it were the
specialists in electrical instruments Nairnc, I lenly. and I.anc. anil the
other British scientist to bring forward a general, mathematical theory
of electricity, Charles Stanhope, Lord Mahon, and also the
experimenter and inspirer of much electrical experimentation.
Priestley. This third committee reported on the dissident Wilson's
recommendation for rounded instead of pointed lightning conductors, a
controversy ideally suited for the talents of Swift, if he had been around
to know of it. Henry Lyons, The Royal Society, t660~1940:A History of Its
Administration under Its Charters (New York: Greenwood, 1968). 19.1

*Royal Society, Minutes of Council 7:314 (17 Mar. 1796).

■"Cavendish had several friends on this committee, such as Sir
Charles Blagdcn, Count Rumford, Charles Hatchctt. Sir Joseph
Banks. Royal Society, Minutes of Council 7:408-10 ( 1 1 June 1801 ).

192

the treatises which have been published, I shall
not pretend to determine; but at all events it is a
thin» very much to be regretted. 4 -

Thomson's impression is confirmed by one of the
first nineteenth-century electricians to notice
( lavendish's work, George Green, who came across it
in a search of the literature after finishing his famous
essay of on the electrical potential functions,
noting that Cavendish's theory "appears to have at-
tracted little attention." 43 In the forty years between
Cavendish's work and Poisson's in 1812, Green said
little had been done in the mathematical theory of
electricity. That a profound, mathematical theory of
electricity was for so long almost totally ignored is a
striking comment on the decay of the mathematical
tradition in late eighteenth-century Britain.

In the early eighteenth century, there had
been a British circle of ardent admirers of Newton's
mathematical philosophy, Roger Cotes, Colin
Maclaurin, and others. They were not replaced.
Newton had urged his followers to go out and
discover the forces of nature the way he had done,
but it had not happened. Newton himself had
been the first to fail, in optics; his immediate
followers failed in other parts of science. By
Cavendish's time scarcely any investigator pursued
Newton's end-in-view of natural philosophy; then,
without warning. Cavendish presented British
scientists w ith a mathematical theory of electricity
modeled after the treatment of gravitation in
New ton's Principia. There was not an electrician in
Britain with the mathematical training to appreciate
w hat Cavendish had done, let alone extend or crit-
icize it. If Cav endish had belonged to a Continental
scientific academy instead of to the British Royal
Society, he might have had an appreciative audience, 44
but then Cavendish would have had to be a
European and not a Briton w hose family defied the
power of the monarch. (On this point, Cav endish w as
at one with Joseph Banks, who wrote to a foreign
colleague that the Royal Society "differs essentially"
from its Continental imitators, which are "associa-
tions of learned men collected together by their
respective monarchs"; speaking for the native mem-
bership of the Royal Society, Banks said that "our
chief boast" is in maintaining the independence of
the Royal Society. 45 ) Cavendish's paper of 1771,
the first work to have the substance of a genuine
successor to New ton's Principia and not merely the
surface and pretension of one, was passed by

Cavendish

almost without comment. Cavendish's experimental
paper on the torpedo received more notice than
did his paper on electrical theory.

There was another reason why Cavendish
was ignored. The topics he addressed were no
longer of central concern to electricians. In his
paper of 1771 Cavendish limited his discussion to
several "principal" matters: the attraction and
reptdsion of bodies, electric induction, the Leyden
jar, and the electrification of air. These phenomena
were generally thought to be adequately understood.
Priestley's History of Electricity contained Priestley's
own investigations of phenomena that were not
adequately understood, and Priestley's queries
suggest the nature of the problems that interested
Cavendish's contemporaries; they had to do mainly
with the connections between electricity and light,
sound, heat, and chemistry. Typical of the thinking
then was Henly's belief, in 1777, that light, fire,
phlogiston, and electricity were "only different
modifications of one and the same principle." 46
Although Cavendish's natural philosophy could
accommodate connections between these subjects,
his work was not directed to them.

Cavendish had begun his electrical researehes
right after his initial publication on factitious air,
which earned him a Copley Medal. After his initial
publication on electricity there was no sign that
anyone comprehended that he might be on the
track of a work that would stand beside Newton's.
He never again published a theoretical paper. It
was, in effect, ten years after he had given up the
idea of publishing his comprehensive electrical
experiments before he appeared in print again with
original research; when he did, it was to return to
the approach and subject of his original success,
the experimental study of airs.

4 -Thomas Thomson. History of the Royal Society from Its
Institution to the End of the Eighteenth Century (London. 1 K 1 2 ). 455.

43 George Green, An Essay on the Application of Mathematical
Analysis to the Theories of Electricity anil Magnetism ( Nottingham, 1828), v.

" Thomas S. ktihn's comparison of the "classical" mathematical
sciences and the "Baconian" experimental sciences would suggest
that had Cavendish been horn a European instead of an Englishman,
he would have had understanding colleagues in the Continental-type
academies of science for his mathematical electricity: "Mathematical
\ersns Experimental Traditions in the Development of Physical
Science," in Kuhn's The Essential Tension: Selected Studies in Scientific

Tradition and Change (Chicago: University of Chicago Press. 1°77).
31-65, on 58.

^Joseph Hanks to ( lonnt W.. 2 June /n.v./. Banks Correspondence.
Kew, 3:3.

"William Hcnly, "Experiments and Observations in Electric-
ity," T'Thl (1777): 85-14.?, on 135.

Electricity

193

The reasons why Cavendish did not publish
his electrical experiments are more complicated
than neglect. What had begun as a second paper
for the Philosophical Transactions became a large
treatise on electricity. 47 He completed several of his
subsequent electrical researches to his satisfaction,
but he was not satisfied with the treatise. His
discovery of the influence of chemical substances
on the capacity of Leyden jars was, we think, what
stopped him temporarily, then for good. His work
on electricity took an inconclusive path similar to
Newton's in the Opticks; before Newton could
know the interaction of light with matter, every-

thing else about matter had to be known, and so it
seemed that in the field of electricity, too,
everything else had to be known first.

47 As an article the "work" would have been long: the material to
be included occupies 11)4 pages of the Maxwell edition of Cavendish's
electrical researches, and it would have expanded into nearly twice
that number of pages in the Philosophical Transactions. The 1771 paper
was itself long, taking up 49 pages in the Maxwell edition and ninety-
four in the Philosophical Transactions, by far Cavendish's longest
publication. It is likely that at some point Cavendish abandoned his
original idea of publishing another article in the Philosophical
Transactions and set out instead to write a book. Maxwell thought that
Cavendish was working on a book, in Cavendish. Set. Pap. 1:13.

CHAPTER 6

/earned Organizations

Royal Society

At the time Cavendish entered the Royal
Society, in 1760, its membership was stable, as it
had not been before and would not be after. During
the twenty years centering on 1760, the average
number of ordinary members was virtually constant,
about 355, whereas it had grown by nearly one
quarter in the thirty years after Cavendish's father
had joined. The foreign membership was now at its
maximum, at about 160, forty percent larger than it
had been thirty years before; thereafter it slowly
declined owing to a deliberate policy of the Society
to stop the escalation of this honorary segment of
its membership. 1

Cavendish did his part to perpetuate, but
not inflate, the membership of the Royal Society.
In his first twenty years, he signed fourteen
certificates for new members. The first time he
signed one, he did so together with his father,
whose name appears first on the certificate for the
Plumian professor of astronomy and experimental
philosophy at Cambridge, Anthony Shepherd.
That was the only time father and son made a
recommendation in common; Lord Charles Caven-
dish, in fact, made only four more recommen-
dations altogether after 1760. Of the candidates
recommended by Henry Cavendish, most were
said to be proficient in natural philosophy (or an
alternative term for it), astronomy, or mathematics.
His preference of fields was clear, but it was not
exclusive; polite literature, natural history,
antiquities, and voyages of discovery were also
cited. He welcomed as members persons who had
been in India and the South Seas, who knew
remote parts of the world firsthand. Some of the
candidates, such as Francis Wollaston, Cavendish
probably had known at Cambridge, but others do
not seem to have been long-term friends, and he
did not sign the certificates of a number of
candidates who became his closest friends, such
as Alexander Aubert, Alexander Dalrymple, and

Charles Blagden. Of the almost one hundred
names that appear together with his on the
recommendations, only a few appear more than
once; Nevil Maskelyne appears on half of them,
and after him in decreasing frequency, come the
keeper of the natural history department of the
British Museum, Daniel Solander, William Watson,
James Burrow, and William Heberden. Several of
these persons are carry-overs from co-signers with
Cavendish's father. 2

In keeping with tradition. Cavendish
invited some of his candidates to meetings of the
Royal Society. Francis Wollaston was one, another
was Timothy Lane, whom Cavendish brought to
five meetings before his election.' Lane was an
apothecary in London who took up the problem of
mineral water where Brownrigg and Cavendish had
left it, closely tying it to pneumatic chemistry.
Before publishing his experiments on the solution
of iron in water impregnated with fixed air in the
Philosophical Transactions in 1769, he submitted
them to Cavendish for judgment. Cavendish's papers
of 1766 and 1767 were Lane's acknowledged
starting point, and the learned world, he said, "had
great reason to hope for many other new and useful
experiments" from Cavendish. 4 Lane spoke of
Cavendish's "known accuracy," which is what

'The council resolved on 19 Dec. 1765 to admit no more than
two foreign members a year until their number fell to eighty.
Excluded, however, from this limit were sovereign princes and their
sons, ambassadors, and foreigners living in England. Into the next
year the council passed a series of other resolutions about foreign
members, the most important being that no foreigner could be
admitted in shorter time than six months, and that he had to be
recommended by three foreign and three domestic members. Royal
Society, Minutes of Council, 5: 146-4K (19 Dec. 1765) and 153-54
(6 Feb. 1766).

-'Royal Society, Certificates, vol. 2. ff. 242. 312. .543; vol. 3, ff. 65.
73, 79, 104, 161, 209, 237, 259; vol. 4, ff. 23, 24, 56.

'Cavendish brought Lane to meetings of the Royal Society on °
Feb., 20 Apr., 4 and 11 May, 8 June, 9 Nov. 1769; Lane was elected
the next year. Royal Society, JB 26 (1767-70).

•'Timothy Lane, "A Letter ... on the Solubility of Iron in
Simple Water, by the Introduction of F'ixed Air," PT 59 ( 1 76'*):
216-27. on 216.

106

Cavendish

Lane was known for too, having recently published
an account of an electrometer for introducing into
electricity a "much greater degree of precision";
with "tolerable accuracy," his electrometer could
measure the "quantity" of electric fluid stored in a
Leyden jar. 5 In 1769, when Cavendish brought
Lane repeatedly to the Royal Society, Lane's work
in electricity probably interested him more than did
Lane's work on mineral water. The Royal Society
extended a scientific exchange that had already
been established between Lane and Cavendish.

In November 1765 Henry Cavendish was
elected to the council of the Royal Society,'' the
first of thirty-four times. Like his father, he almost
never missed a meeting. In his first year on the
council, other than for the two secretaries, Henry
Cavendish attended with greater regularity than
any other member. For the next twenty years he
was on the council about half of the time; for the
last twenty-five years, through 1809, he was on the
council every year. His service on special commit-
tees appointed by the council was nearly as
consistent. 7 I Ie was extensively involved in the two
big projects initiated by the Society during his
time, the observation of the transit of Venus in
1769 and the experiment on the attraction of
mountains in 1774. He drew up plans for a voyage
of discovery' to the Arctic. I Ie worked on changes in
the statutes of the Society and on the printing of
the Philosophical Transactions. Fie was routinely
appointed to committees concerned with the state
of the instruments of the Royal Society and the
Royal Observatory. And, as we have seen, he was
on committees called into being by requests of the
government. He was appointed to twenty-three
committees, more or less,* and he took on many
assignments for the Society that did not involve a
committee but at most an instrument-maker to
work with him. Altogether, on special committees
Cavendish worked with sixty Fellows. Since the
work of the Society was spread around, usually
other Fellows appeared on only one committee
w ith him. The exceptions were Nevil Maskelyne,
the astronomer royal, and the astronomer Alexander
Aubert, who was an expert on meteorological as
well as astronomical instruments.''

In addition to serving on one-time commit-
tees, Henry Cavendish, like his father, was often
elected one of the annual auditors of the treasurer's
account. It happened the first time during his first

year on the council, 1766; serving with two stalwart
members James Burrow and Ceorge Lewis Scott,
Cavendish reported to the council in the name of
the three auditors. 10 He could accept that much
prominence. The treasurer's balances were small,
which did not diminish the responsibility of the
auditors; Cavendish was joined in subsequent years
by other members of impeccable reputation, such
as Maskelyne and Benjamin Franklin.

Like his father again. Cavendish served
regularly on the committee of papers." This
committee attracted the ablest scientific men,
regardless of their own habits in the matter of
publication; some of them, such as Maskelyne and
William Herschel and Cavendish himself, were
themselves authors of many papers in the
Philosophical Transactions, but others, such as
Aubert, published nothing or next to nothing
there. In addition to attending the meetings of the
committee, which took place monthly as needed,
the members had homework. On any particular
paper, the committee would make one of several
decisions: to print, not to print, or to withdraw or
postpone. If postponed, the paper might be referred
to one or two members; this happened often to
Cavendish, and among his papers we find a good
many studies of his own that originated this way.

During Cavendish's first year, 1766, the
council was occupied with John Canton's experi-
ment on the compressibility of water, which his
father had pretty much taken charge of. Caven-
dish's first work for the Society was on the subject
for which his father had earned the Copley Medal,
thermometers.

In June, 1766, the council began its
painstaking preparations for observing the transit of
Venus of 1769. This was the second of these rare,
paired transits, which offered an accurate measure

'Timothy Lane, "Description of an Electrometer Invented by
Mr. Lane; with an Account of Some Experiments Made by Him
With It." PTS1 (1767): 451-60, on 451.

'Entry for 30 Nov. 1 765. Royal Society, JB 25:663.

'From a survey of the Royal Society, Minutes of Council, vols.
5-7. 1763-1810.

"It depends on how one counts. Committees were often renewed
becoming virtually new committees with the same or a redefined task.

'Cavendish served on eight committees with Maskelyne and as
many with Aubert.

l0 Royal Society. Minutes of Council, 5:163 (24 Nov. 1766). One
week later, on 30 Nov. 1766. p. 167. Cavendish reported for the
auditors.

"l'rom a survey of the bound volume of minutes of the Royal
Society's committee of papers, vol. 1, covering 17HO-1H2X.

ght«J maierial

I. earned ( irgtitiiztttions

197

of the sun's distance. It had been only four years
since the Society had finished with the 1761 transit,
with rather disappointing results. Instruments from
the earlier transit were reassembled, and observers
were selected, for example, Roger Joseph Boscovich,
Fellow of the Royal Society and professor of
mathematics at Pavia. For those involved, it was
their last chance, since they would not be around
for the next transit of Venus, a hundred years off.
The first study of the transit of 1769 to be brought
before the council was a letter by Henry Cavendish
to Lord Morton, president of the Society, on the
best places in the world to observe the transit. 1 -
Charles Cavendish had taken a leading part in the
work on the first transit; Henry Cavendish would
take a leading part in the work of the second.

We should point out that Cavendish had not
yet published any research, though the first part of
what would be his first publication, on factitious
air, had just been read to the Society, at the end of
May. He had been a Fellow for six years, and in
this time he had obviously made known his talents
and his willingness to serve.

Cavendish studied the observations of the
earlier transit of Venus of 1761, and he did this
while he was still in the middle of his experiments
on air. There was a connection between these
studies through the air, or atmosphere, of Venus,
which affected the observed times of the external
and internal contact of the limbs of Venus and the
sun. At the time of the first transit, the effect of the
atmosphere of Venus had not been considered, with
the result that the reported times of contacts of Venus
and the sun were wildly discordant." By making dif-
ferent assumptions about the elastic fluid consti-
tuting the atmosphere of Venus, Cavendish
computed the errors of observation owing to the re-
fraction of light passing through it from the sun to the
earth. 14 Before Cavendish was done with the transit
of Venus of 1769, he had written over 150 pages, a
large work of which nothing appeared in print. 15

As it turned out, observations of the second
transit did not result in an unambiguous figure for
the distance of the sun, but they were a great
achievement, and there were side benefits. The
Society had been shown the work it could expect
from Cavendish, for one. The second transit of
Venus marked the beginning of his service as a
committeeman of the Society, possibly its most
called up and certainly its most versatile.

We turn next to the other great project of
the Royal Society during Cavendish's membership,
the experiment on the attraction of mountains."'
This was an experiment on gravitation and on the
earth, on a universal power and a particular body of
the universe. Cavendish's work on this experiment
foreshadows the most famous of his experiments
twenty-five years later, the weighing of the earth.
The experiment on the attraction of mountains
came close upon the heels of the observation of the
transit of Venus in 1769. In 1771 Maskelyne sent
Cavendish a letter containing two theorems for
calculating the gravitational attraction of mountain-
like geometrical solids, a hyperbolic wedge and an
elliptic cuneus; Cavendish wrote on the back of the
letter his version of Maskelyne's two formulas. 17
This is our earliest evidence that the experiment
on the attraction of mountains was underway, the
object of which was to determine the average
density of the earth. On the face of it, this experi-
ment seems remote from the Society's recent
concern, but the goals of the observation of the
transits of Venus and the experiment on the
density of the earth were much the same. They
were to measure the earth in relation to its home in
the universe, the solar system, by determining a
standard in each case, a distance in the first and a
quantity of matter in the second. The distances of
the planets were expressed in terms of the distance
of the earth from the sun; likewise, the densities of
the sun and some of the planets were known only
relatively, so that the density of the earth had first

'-Royal Society. Minutes of Council 5:156 (5 June 1766) anil 157
(19 June 1766). Cavendish would later be appointed to a committee
of eight to consider places tor observing the transit. Ibid.. 5:1S4 (12
Nov. 1767).

"I I. Spencer-Jones, "Astronomy through the Eighteenth ( lentury,"
in Natural Philosophy, published by the Philosophical Magazine in
1948, pp. l<)->7. on p. 16.

14 Henrv Cavendish, "On the Effects Which Will Be Produced in
the Transit of Venus by an Atmosphere Surrounding the Bod} of
Venus," Cavendish Mss V III, 11.

l5 In addition to the above "Thoughts," letter to Morton, and
"On the Effects ... of an Atmosphere," Henry Cavendish wrote
these studies: "Computation of Transit of Venus 1761. 1769,"
"Method of Finding in What Year a 'Transit of Venus Will Happen."
"Computation of Transit of 1769 Correct," and "Computation for
1769 Transit," Cavendish Mss VIII, 30-33.

"''The discussion of the attraction of mountains is based on
Russell McCormmach, " The Last Experiment of Henry Cavendish,"
in 'No Truth Except in Details': Essays in Honor of Martin J. Klein, eds.
A. J. Kox and D. M. Siegel (Dordrecht: Klewer Academic Publishers,
1995). 1-30. See pt. 4, ch. 7, n. 1.

"Nevil Maskelvne to Henry Cavendish. 10 Apr. 1771,
Cavendish Mss V III, 4.

198

to be known to know the density of the othct
bodies. IK It stands to teason that the same persons
would work on the transits of Venus and the
density of the earth.

We will briefly review some well-known
historical facts about the attraction of mountains.
Newton had concluded, as had Huygens, that
owing to the attraction of the earth and to the
centrifugal force of the earth's rotation, the shape
of the earth was an ellipsoid of revolution; that is, a
spheroid flattened at the poles. The Cartesian
astronomer Jacques Cassini held the contrary
opinion: on the basis of French measurements, he
concluded that the earth is indeed a spheroid but
one that is elongated at the poles, like an egg on
end. The clear implication was that if Newton was
right, the length of a decree of latitude is longer at
the poles than at the equator, but if Casini was
right, the length of a decree is longer at the
equator. To settle this question, two expeditions
were sent out, one in the direction of the north
pole, the other in the direction of the equator. The
question was answered in favor of Newton and his
supporters, the "earth flatteners." This decision
depended on the use of astronomical instruments,
which is how mountains enter this study of the
shape of the earth.

Peru is a land of mountains. If gravitation is
a universal law, as Newton said, then a plumb bob
in the vicinity of a mountain should he drawn aside
by its gravitation. Newton calculated the effect: a
hemispherical mountain of earth matter with a
radius of three miles should deflect a plumb-line
by a minute or two of arc. He thought that this
effect was too small to measure, an opinion which
was received by eighteenth-century precisionists as
a challenge. Near the equator, the French party
under Pierre Bouguer and I). M. de la Condamine
did an experiment to see if the attraction of
mountains did really exist. (It was a practical
question for them, for they were measuring a
degree of latitude, and astronomical instruments
depend on a plumb-line to establish the vertical.)
With a quadrant oriented by a plumb-line, they
measured the distance between stars directlv
overhead in two places, one beside a mountain and
one on a plain. They did observe a deflection, and
in the expected direction, but thev could not
measure it with the instruments at hand. Upon his
return from the expedition in 1744. Bouguer said

Cavendish

that he would like to see the experiment on the
attraction of mountains repeated under proper
conditions in Furope. His La figure de la terre,
detenu i nee par les observations de Messieurs De la
Condamine et Bouguer . . ., published in 1749, was to
be Cavendish's starting point in his work on the
problem. 1 ''

The figure, density, and internal structure
of the earth are connected properties, which in turn
are connected to a seemingly remote phenomenon,
the precession of the equinoxes. This precession is
the slow movement of the earth's axis of rotation
relative to the stars caused by the attraction of the
sun and moon on the earth's equatorial bulge. In a
carefully drafted but unpublished paper on the
precession of the equinoxes, Cavendish tried to
reconcile Bouguer's figure of the earth obtained by
measurement with the figure that agrees with the
variation of gravity with latitude, as determined by
theory and tested by pendulums. He could not do
it without assuming a "very improbable hypothesis
of the density of the earth" or denying the well-
founded gravitational theory. The explanation, he
thought, lay with the gravitation of the high
mountains in South America where the French
made their equatorial observations. 20 Cavendish
was inclined to favor theory over measurement in
this case, as the French measurements were
probably off owing to the attraction of mountains.

The transit of Venus in 1761 sent observers
around the world with instruments that, as it
turned out, recorded the presence of nearby
mountains. Maskelyne, for example, was on St.
Helena, where clouds prevented him from
observing the transit, so the main point was lost.
But while he was there he did another experiment

'"Charles Mutton, "An Account of the Calculations Made from
the Survey and Measures Taken at Sehehallien, in Order to Ascertain
the Mean Density of the Karth," PT 68 (1778): 689-788, on 784.
B. I-;. Clotfelter, "The Cavendish Experiment as Cavendish Knew
It," American Journal of Physics 55 (1987): 210-13, on 211.

"In his System of the World, Newton was discouraging on the
prospect of detecting the attraction of mountains: "Nay, whole
mountains will not be sufficient to produce any sensible effect. A
mountain of an hemispherical figure, three miles high, and six broad,
w ill not. by its attraction, draw the pendulum two minutes out of the
true perpendicular. . . ." Sir Isaac Newton's Mathematical Principles of
Natural Philosophy and His System of the World, trans. A. Motte, rev. F.
Cajori, 2 vols. (Berkeley and Los Angeles: University of California
Press. 1962) 2: 569-70. Derek Howse, Nevil Maskelyne: The Seaman s
Astronomer (Cambridge: Cambridge University Press, 1989), 129.

-'"Henry Cavendish. "Precession of Equinoxes," Cavendish Mss
Mil. 9:14-15.

Learned Organizations

199

to find the parallax of the brightest and supposedly
closest star, Sinus; that would give not the distance
of the earth from the sun but its distance from a
fixed star, another measure of cosmological signifi-
cance. Astronomers such as Bradley had looked
hard for this parallax, using the earth's orbit as base
line. St. Helena being mountainous, Maskelyne
heeded the warning implied in Newton's calcula-
tion by taking into account the attraction of the
mountains on the plumb-line of his zenith sector.
His instrument proved defective, so nothing came
of this attempt either. It had long been known that
a pendulum beating seconds is shorter near the
equator than at higher latitudes. Newton and
Huygens and those who came after them
recognized that comparative measurements of the
lengths of a seconds pendulum at different
latitudes could determine the shape of the earth.
Experiments with pendulums had been made at
various places, and Maskelyne made another
experiment at St. Helena. Lord Charles Cavendish
had approved of Maskelyne's experiment and
pendulum clock, and Maskelyne communicated a
paper to the Royal Society through Cavendish,
which reported the lessened gravity on St. Helena
compared to the gravity at Creenwich, but
Maskelyne did not draw from it conclusions about
the figure of the earth. As he explained to
Cavendish, such conclusions depend not only on
gravity but on the "internal constitution and
density "of the earth. There had to be experiments
of "other different kinds," which he did not specify
but which he would soon pursue. 21 Charles Mason
was another designated observer of the transit of
Venus of 1761 who encountered the attraction of
mountains. On his way home from the Cape of
Cood Hope where he had gone to observe the
transit, Mason with his associate Jeremiah Dixon
were hired to settle the old boundary dispute
between the colonies of Pennsylvania and
Maryland. During the five years they spent at this
job, they also measured the length of a degree of
latitude. In reviewing their measurement,
Maskelyne said that lie did not think it was flawed
by the attraction of any mountain. 22 Cavendish
took exception. By taking into consideration the
Allegheny Mountains to the northwest and the
deficiency of mountains in the Atlantic Ocean to the
southeast, he calculated that Mason and Dixon's
degree could fall short by sixty to one hundred Paris

toises. One toise equaling about two meters, this
was a considerable error. Others, he pointed out, had
made the same kind of etror in measuring a
degree. 2 "' The best way to determine the form of the
earth, Cavendish thought, was not by measurement
but by gravity. 24 The form of the earth, the length of
a degree, the attraction of mountains, the density of
the earth, and the precession of the equinoxes
were a tangle of problems.

In 1771, as we have seen, Cavendish and
Maskelyne consulted about the attraction of
mountains. For Maskelyne, Cavendish worked out
rules for finding the attraction of a particle at the
foot of and at a distance from geometrical solids —
slabs, wedges, and cones — generated by lines and
planes and obeying the law of universal gravitation.
Cavendish then turned to the subject of scientific
interest, the real world of attracting bodies, which
include the great irregular masses that the earth
throws up. These masses distort astronomical
observation but, as if in compensation, they also
provide a means for measuring the density of the
earth. Combining his geometrical representations
of mountains with the French observations with
pendulums on the real mountains of the equator,
Cavendish made several estimates of the mean
density of the earth, which fell between 2.72 and
4.44 times the density of water. These estimates,
his earliest, required a correction, since the beating
of pendulums depend not only on latitude and
nearby mountains but also on the internal structure

21 Ncvil Maskelyne. "Observations on a Clock of Mr. John
Shelton, Made at St. Helena: In a Letter to the Right Honourable
Lord Charles Cavendish, Vice-President of the Royal Society," PTS2
( 1 762): 434-47, on 436, 442.

22 Nevil Maskelyne, "Introduction to the Following Observations,
Made by Messicrs Charles Mason and Jeremiah Dixon, for
Determining the Length of a Degree of Latitude, in the Provinces of
Maryland and Pennsylvania in North America," PT SH (1768):
270-73, on 273. Mason and Dixon's measurement, Maskelyne said,
could not have been affected by mountains because the degree of
latitude passes through level country. Maskelyne noted that Roger
Joseph Boscovich was the first to take into account the effect of the
attraction of mountains in his measurement of the length of a degree
of latitude in Italy.

2, Nevil Maskelyne, "Postscript by the Astronomer Royal." PT
58 (1768): 325-28, on 328. This postscript follows the paper by
Mason ami Dixon on the length of a degree. Maskelyne took back
what he had said, the reason being that "Cavendish has since
considered this matter more minutely" and demonstrated the effect
of the mountains. Henry Cavendish, "Observations on the Length of
a Degree of Latitude," Cavendish Mss VIII, 16.

24 One reason he gave is the better fit with the precession of the
equinoxes. Henry Cavendish. "Paper Oiven to Maskelyne Relating
to Attraction & Form of Earth," Cavendish Mss VI(b), 1:18.

200

of the earth. To give Maskelyne an idea of this
correction. Cavendish invoked an entirely different
kind of evidence, Canton's experiment on the
compressibility of water, which his father had
confirmed. Supposing, he said, that even if the
surface and the interior of the earth are of the same
substance, the interior will be compressed.
Beginning with Canton's demonstration that the
density of water is increased 44/1, ()()(),()()() by the
pressure of one atmosphere, and making a
quantitative assumption about the compressibility
of earth relative to that of water. Cavendish
constructed a table of the densities of the earth at
different distances from its center. He deduced
that the mean density of the earth should be more
than eleven times the surface density, a value
much higher than the French (and the value he
later measured). He did not comment on it, since
the interior of the earth in his calculations was
purely hypothetical. This and only this far could
Cavendish go with his theoretical reasoning and
observations made by others with the seconds
pendulum. What were needed were new
observations from a new experiment.- 5 The new
experiment was to be based on Cavendish's
alternative, practical way of finding the density of
the earth, w hich was to measure the "deviation of
the plumb line at the bottom of a mountain by
taking the meridian altitudes of stars." Although it
was more difficult than the method of the seconds
pendulum, it was "more exact," since it was less
affected by irregularities in the internal parts of the
earth. In the middle of 1772 Maskelyne proposed
such an experiment to the Society. The council
appointed a committee to consider it and to draw
on the treasurer as needed.-''

In a letter to ( lavendish at the beginning of
1773, Maskelyne said that he had made a copy of
Cavendish's rules, which were "well calculated to
procure us the information that is wanted." 27 In a
paper written for his fellow committeeman
Benjamin Franklin, Cavendish explained what
sorts of mountains are best. The want of attraction
of a v alley, he said, is as good as the attraction of a
mountain and perhaps better. - H In the middle of
1773 the council sent Charles Mason off on
horseback into the Scottish Highlands to observe
mountains and valleys suited for the experiment. 21 '
In early 1774, a year and a half after the committee
had been formed, its mind was made up. From

Cavendish

Mason's survey, their choice was a 3547-foot granite
mountain in Pershire, Maiden's Pap. 30 Its alterna-
tive and equally descriptive name, "Schiehallien,"
meaning "constant storm," was preferred by the
Society. This mountain was made to Cavendish's
order: big, regular, detached, with a narrow base in
the north-south direction on either side of which
observations could optimally be taken. Losing no
time, the committee selected as their experimenter
Charles Mason, who turned them down and with it
unforseen glory. The committee next turned to
Maskelyne's assistant Reuben Burrow. It was the
dead of winter and the committee had time for
second thoughts: the Creenwich assistant did not
seem equal to this important experiment, the
committee thought, so it turned to Maskelyne, who
accepted the assignment. 31 Burrow determined the
size and shape of the mountain, and Maskelyne
observed forty-three stars from it. Cavendish super-
vised the repair of one of the instruments for the
experiment. When the experiment was done, Cav-
endish and C. J. Phipps went over Burrow's scarcely
legible papers from the field.' 2 The attraction of
Schiehallien proved measurable, if with not much
to spare, as is evident from Cavendish's attempts to
decide its likelihood in advance."

»Ibid. 2-16, 19.

-' Ibid. 19-20. Ncvil Maskelyne, "A Proposal for Measuring the
Attraction of Sonic Hill in This Kingdom by Astronomical
Observations." PT 65 (1772): 495-99. Royal Society. Minutes of
Council 6: 145 (23 July 1772). In addition to Cavendish, the
committee to consider the experiment on the attraction of
mountains contained Maskelyne, Benjamin franklin, Samuel
Horsley, and Daines Harrington. The king approved the use of
money left over from observing the transit of Venus for the
experiment on attraction.

-'Ncvil Maskelyne to Henry Cavendish, 5 Jan. 1773. Cavendish
\lss X(b); published in full in Cavendish, Set. Pap. 2:402. Having
made his copy. Maskelyne returned Cavendish's "Rules for
Computing the Attraction of Hills." The preliminary version of that
paper is Henry Cavendish, "Thoughts on the Method of Finding the
Density of the Karth by Observing the Attraction of Hills."
Cavendish Mss Vl(b), 2 and 0.

-'"I lenry ( lavendish, "On the Choice of I Mils Proper for Observing
Attraction Given to Dr Franklin," Cavendish Mss Vl(b), 3:5.

-"'Royal Society. Minutes of Council 6:180 (24 June 1773) and
185-86 (29 July 1773).

'"'In Cavendish's papers is an untitled study of Maiden's Pap,
Cavendish Mss. Misc.

"-'Roval Society, Minutes of Council, (>:2I()-1 1 (27 Jan. 1774) and
234(5 May 1774).

'-Roval Society. Minutes of Council. 6:2IH (17 Feb. 1774), 242
(II Aug. 1774). 244 (11 Oct. 1774). 255 (22 Dec. 1774). 2i>0-61 (30
Mar. 1775), and 267-<,9 (27 Apr. 1775).

"Before the experiment. Cavendish prepared a table of
dev iations of the plumb-line in seconds of ate for mountains made of
cones and spherical segments. If the observations on a steep slope-
could be made with the same accuracy as on level ground. Cavendish

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I .earned Organizations

JO/

On the basis of the experiment and
Newton's "rules of philosophizing," Maskelyne
told the Royal Society in July 1775 that "we are to
conclude, that every mountain, and indeed every
particle of the earth, is endued with the same
property /attraction/, in proportion to its quantity of
matter," and further that the "law of the variation
of this force, in the inverse ratio of the squares of
the distances, as laid down by Sir Isaac Newton, is
also confirmed. " M For this work, Maskelyne was
awarded the Copley Medal in 1775. In his address
on the occasion, John Pringle, the president of the
Society, said that now the Newtonian system is
"finished" and that every man must become a
Newtonian." Maskelyne's and Prinze's conclusions
could have come as no surprise to Cavendish, who
in any ease was interested in the quantity the
experiment addressed, the mean density of the
earth. That quantity had to wait for the calculations
of the mathematician Charles Hutton, who had
been hired by Maskelyne. Not until 1778 did
Hutton finished his paper of some hundred pages
of "long and tedious" figuring. To explain why it
took him so long, Hutton said that new methods of
calculation had to be invented, and he also said
that Cavendish had supplied him with some of
these. It came down to this: the ratio of the mean
density of the earth to the density of the mountain
is 9 to 5. Hutton pointed out that the density of the
mountain was unknown and only an empirical
study of its internal structure could determine it.
Nevertheless Hutton expressed the result in a
more satisfying form: by assuming that the
mountain is "common stone"; the density of
common stone being 2Yz, the density of the earth is
4Y: times the density of water. Newton's best guess
was that the density of the earth is between 5 and 6
("so much justness was even in the surmises of this
wonderful man!"). Reminding his readers that this
experiment was the first of its kind, Hutton hoped
that it would be repeated in other places. 36

Legend has it that Maskelyne threw a
bacchanalian feast for the inhabitants around
Shiehallion." It is hard to picture the stodgy
Maskelyne taking part in this affair and impossible
to imagine Cavendish. But, of course, Cavendish
was not there. Just as Cavendish did not travel to
observe the transit of Venus, he did not go to
Scotland but studied its mountains and valleys in
his father's house on Creat Marlborough Street in

London. Cavendish had done the comprehensive
planning of the experiment, but he did not make
observations from the mountain or make final
calculations of the earth's density. Others did these
things and they published their results. In the
landscape of the experiment. Cavendish may be
likened to the valley as opposed to the mountain.
As he demonstrated, the valley offers great
accuracy, but the experiment was done on a
mountain, a feature which draws the eye more than
does the valley. Cavendish's work on the
experiment went unseen except by others who
worked on it. It was entirely characteristic of him.
This work for the Royal Society was as important
to him as his private researches and as hidden from
the public eye.

Cavendish served on committees of the Royal
Society for thirty-odd years after the experiment on
the attraction of mountains. During that time the
Society undertook nothing again so fundamental.
There were, however, important domestic rearrange-
ments. Crane Court, the meeting place of the
Society, was cramped, and when Joseph Banks

reasoned that the observer should be able to determine the
difference in the zenith distanees of the stars on the two sides of the
mountain with "tolerable certainty to .V," and would not be "likely
to err more than Upon this estimate of accuracy. Cavendish

further reasoned that "if the mean density of the Earth is not more
than 7 times greater than that of the surface the effect of attraction
must pretty certainly be sensible & it is an even chance that it will
come out such that we may with tolerable certainty pronounce to be
not owing to the error of observation tk even if the mean density is
14 times greater than that of the surface the effect of attraction will
most likely be sensible . . ." "Thoughts on the Method of Finding
the Density of the Earth by Observing the Attraction of Hills."
unnumbered sheet. There are a good many assumptions behind this
cautious statement about tolerable certainty. To Franklin. Cavendish
w rote: "It will be needless to send an account of any hill or valley it
the sum of its deviations is less than 50" or 60" as I am in hopes
some may be found nearer home near as good as that." "On the
Choice of Hills Proper for Observing Attraction Given to Dr.
Franklin," unnumbered sheet. Maskelyne's results fell just within
Cavendish's estimated limits of tolerable certainty. The apparent
difference in the position of the stars at the two sides of the
mountain was 54.6", and the difference in latitude of the two
stations, as determined by measuring, was 42.94"; so the difference,
11.6", was the true combined effect of the two attractions, or 5.8"
was the effect of the attraction of Schiehallien on the plumb bob of
the zenith sector.

'\evil Maskelyne. "An \ccount of Observations Made on the
Mountain Schehallien for Finding Its Attraction," PT 65 (1775):
500-42, on 532.

"John Pringlc. A Discourse on the Attraction of Mountains. Delivered
at the Anniversary Meeting of the Royal Society. November .10. 7 775
(London, 1775); the remark on the Newtonian system comes at the
end of the discourse.

"'Hutton, "An Account of the Calculations." 689-90, 750. 766,
781-83, 785.

"Howse, Maskelyne. 137-38.

202

became president in 1778 he approached the
government for new quarters. These were decided
to be in Somerset House, and Cavendish was
appointed to a committee to meet with the
architect about fitting up new apartments there.™
Having examined the meteorological instruments
of the Society a few years before, Cavendish was
charged with seeing to the best placement of these
instruments in the new location. 3 '' True to form, in
his report to the council Cavendish was most
concerned with the "error" arising from alternative
placements, but he also watched for "any eye
sore." 4 " He was appointed to the committee to
direct the keeping of the meteorological journal
from its new location. 41 Somerset House was better
located than Crane Court, and most important, it
had more space though it was not exactly
spacious.- 1 - In the meeting room, the president sat
in a grand, high-backed chair, like a judge, well
above the table at which the secretaries sat. The
ordinary members sat on hard benches with rail
backs resembling pews and like them discouraging
sleep. For the last thirty years of his life, Cavendish
came regularly to Somerset House, where he sat
beneath the paintings of illustrious past members,
crammed on the walls one above another. (By
refusing to sit for a painting, he insured that he
would not be exhibited on those walls exposed
helplessly and forever after to the prying eyes of
strangers.) The next move of the Society was not
until 1857, when its new home was Burlington
House in Piccadilly, which had belonged to the
( lavendishes.

As we have seen in his work for the Royal Society
on the transit of Venus and the attraction of
mountains. Cavendish stayed at home, leav ing it to
other Fellows to make the necessary expeditions
and observations in the field. A related activity from
which Cavendish likewise stayed home was voyages
of discovery, but he was fully involved in the
scientific preparations for them in the Royal Society.

Persons who brought back scientific informa-
tion from the ends of the earth had a particular
appeal to Henry Cavendish, who recommended a
good many of them for fellowship in the Royal
Society. To give some examples: in 1774 Robert
Barker, recent commander in chief in Bengal; in
1 775 James ( look, the commander of two voyages of
discovery and about to make his third; and in 1780

Cavendish

James King, captain in the royal navy recently
returned from a voyage of discovery in the South
Seas. 4 ' To dine at the Royal Society Club,
Cavendish invited travelers such as the naval captain
and voyager of discovery Constantine John Phipps. 44
His private physician, John Hunter (the "other"
John Hunter), was a voyager as well as a pioneer in
anthropology. Cavendish's library was stocked with
books of voyages and travels and maps, in which
department it was kept up to date. 45 Cavendish's
interest in the wide world and in the people who
knew it from experience is well documented.
England was a seafaring nation and London was its
capital, and the Royal Society offered an open
invitation to any and all travelers who had a story to
tell. For a homebody with a curiosity about the
world, Cavendish was precisely located.

In the second half of the eighteenth century
the world was still very incompletely explored by
Europeans, and there were practical reasons,
forcmostly trade and power, why a country like
Britain should know it better. In 1764 and again in
1766, the British admiralty sent ships to distant
seas to make discoveries, with unimpressive
results. This disappointment might have spelled
the end of such voyages for a time, but for the
Royal Society, which soon promoted a new
justification, the second transit of Venus in 1769.
The Society appealed successfully to the king for
money again and to the admiralty for a ship for the
purpose, the Endeavour. The admiralty appointed
James Cook commander of the ship, and the Royal
Society appointed Cook an observer of Venus. The

'"Minutes of Council. Royal Society, 6:397 (16 Mar. 1780).

'"Minutes of Council. Royal Society, 6:439 (6 July 1781 ).

4 "Minutes of Council. Royal Society, 6:440-42 (12 Aug. 1781).
The concern for placing the meteorological instruments continued,
leading to a committee of Cavendish, Alexander Aubert, William
Heberden, Jean Andre Deluc, William Watson, and Francis
Wollaston: ibid. 7:62 (12 Feb. 1784).

♦'Minutes of Council. Royal Society, 7:138 (19 Jan. 1786).

4: D C. Martin. "Former I Iomes of the Royal Society," Notes and
Records of the Royal Society 22(1967): 12-19, on 16.

J, Royal Society. Certificates, 3:209. 237, and 4:56.

■"Archibald Geikie, Annals of the Royal Society Club (London:
Macmillan. 1917), 234.

45 The catalogue of Cavendish's library has 29 pages of entries on
voyages and travels, 15 on geography, and 18 on maps. Taken
together, these categories occupy more pages of the catalogue than
astronomy or mathematics or any science other than natural
philosophy. The catalogue is in the Devonshire Collection at
Chatsworth. Examples of Cavendish's ongoing purchases are William
Bligh's Voyage to the South Sea in His Majesty's Ship the Bounty . . .
(London, 1792). and Thomas Forrest's A Voyage from Calcutta to the
Mergui Archipelago on the Last Side of the Hay of Bengal ( I .ondon. 1 79Z).

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203

wealthy naturalist and future president of the
Royal Society Joseph Banks, with a retinue,
accompanied Cook, as did an assistant from the
Royal Observatory together with scientific-
instruments from the Royal Society. After making
observations of the transit on Tahiti, Cook went
south to make geographical discoveries. It was
commonly believed that for the earth's stability, the
preponderance of the land masses in the northern
hemisphere had to be balanced by a yet-to-be-
discovered southern continent. There were firm
believers in this continent such as Dalrymple (who
had been turned down for the command of the
Endeavour) and, on the voyage, Banks. There were
also disbelievers on board, Cook among them. On
this voyage, the question of the southern continent
was not settled, but Cook made great discoveries,
which persuaded the admiralty to send him on
another in 1772, this time, at Cook's suggestion,
definitely to prove or disprove that hypothetical
continent; he disproved the existence of any
continent other than a possible permanently frozen
land. 4 '' In the wake of Cook's southern voyages, the
Royal Society proposed, and the king agreed to, a
voyage in the other direction, northward, 47 the
primary object of which was to settle another
practical question, that of the existence of a shorter
route to the East Indies across the north pole, the
hopefully designated Northwest Passage. The
foremost champion in the House of Commons of
the naval administration Constantine John Phipps
was put in command of two frigates, and the
astronomer Israel Lyons was appointed to accom-
pany him. Cavendish was on the Royal Society's
committee for drawing up instructions; 48 in
Cavendish's papers there are several drafts of his
instructions, parts of which are quoted in Phipps's
account, A Voyage Towards the North Pole. m One
instruction has to do with taking the temperature
of the sea, since few observations had ever been
made of it (or of its saltiness, and his instructions
also say to bottle some sea water). That
temperature was to be taken by two methods, one
using Lord Charles Cavendish's self-registering
thermometer, as recommended in his publication of
1757. Since that paper was written, Henry
Cavendish pointed out, John Canton had shown
that spirit of wine and other fluids are com-
pressible, which would make the thermometer
appear colder than it truly was. In light of this

source of error, and of another regarding the
variable rate of expansion of spirit of wine with
temperature, Cavendish provided Phipps with
corrections, which he derived with the help of
Deluc's experiments on the expansion of spirit of
wine. 50 With Lord Charles Cavendish's thermometer,
Phipps measured the temperature of the sea to an
unprecedented depth, 780 fathoms, where the
reading was 26 degrees. From repeated trials, the
accuracy of the thermometer was found to be not
greater than two or three degrees. 51 By the second
method, buckets with valves were used to bring
deep water to the surface, where its temperature
was measured. Parties going ashore were instructed
to make observations and measurements, which
were spelled out by Cavendish. They were to
measure the temperature of well and spring waters,
for that was the "likeliest way of guessing at the
mean heat of the climate." They were also to
observe the corona of the aurora borealis in relation
to the earth's magnetic pole and to note any
irregularities of the dipping and horizontal needles."
Cavendish had never seen an "ice mountain"
(berg) and never would, but if Phipps's party could
get close enough, they were to bore a hole in an ice
mountain and insert a thermometer, and to melt a
piece of it and bring it home in a bottle for
Cavendish to examine, and at the same time they
should observe the texture of the ice and see if

■"Hector Charles Cameron, Sir Joseph Banks, KB., P.R.S. The
Aliform/ of the Philosophers (London: Batchworth, 1952), 6-15, IK. 1.
Kaye, "Captain James Cook and the Royal Society," Notes and
Rerords of the Royal Soriety 24 (1969): 7-18. J. C. Beaglehole, "Cook,
James," DSB 3:396-97.

47 After Daines Barrington, F.R.S., had spoken with the secretary-
Lord Sandwich, the council of the Royal Society formally wrote CO
him proposing a northern voyage with practical and scientific ends.
Royal Society, Minutes of Council, 6:160-61 (19Jan. 1773).

4 *Royal Society, Minutes of Council, 6:172-73 (22 and 29 Apr
1773). The instructions for Phipps's voyage were drawn up by
Cavendish, Nevil Maskelyne, Samuel Horsley, and Matthew Maty.
Charles Richard Weld. A History of the Royal Soriety, vol. 2 (London,
1848), 72.

4, Henry Cavendish, "Rules for Therm, for Heat of Sea," 24
numbered pages of a draft. «ith much crossing out. Cavendish Mss,
111(a): 7. "To Make the Same Observations on the Flat Ice or Fields
of Ice as It Has Been Called, " part of a 10-page manuscript, ibid..
Misc. There is a second draft of the instructions about ice fields,
found among Cavendish's Journals, ibid., X(a). Cavendish's
instructions for the use of his father's thermometer are quoted in
Constantine John Phipps, A Voyage Towards the North Pole, Undertaken
try His Majesty's Command, 177.1 (London, 1774). 145.

5 "Phipps, Voyage ! 4S — 47 Jean Andre Deluc's experiments were
given in his Rerherrhes sur les modifirations de P atmosphere .... 2 vols.
(Geneva, 1772) 1:252.

"Phipps, Voyage, 27, 32-33, 142.

C.ircciulish

roots of trees and plants were imbedded in it and
try to determine where it was formed. "As a theory
frequently enables people to make observations
which would otherwise escape them," Cavendish
said, "I will hint they /ice mountains/ may perhaps
be formed on shores consisting of rocky islands with
narrow channels between by the snow & ice falling
from the sides of the rocks into the channels in the
water & filling them up & that in the spring they are
forced out by storms & the tides." 52 Cavendish's
directions were clear and complete with rationale,
including (in passing) one of the best arguments for
the usefulness of theory in science; namely, as a
stimulus to extraordinary observation.

Phippss observations with a seconds
pendulum by George Graham gave a figure for the
earth that was the closest yet to Newton's
calculation. He kept his two clocks for finding
longitude, one by John Arnold and one of the
Harrison type by Lareum Kendall, in boxes screwed
down to shelves of the cabin, each with three locks,
one key kept by the captain, one by the first
lieutenant, and one by Lyons. 5 ' 1 He brought back a
befitting treasure chest of scientific information,
though on the principal question of the Northwest
Passage, the voyage prov ed inconclusive. 54

'The great trading companies, like the
government, were, in effect, a part of the method
of science in eighteenth-century Britain. Through
Cavendish, scientific observations made on
voyages between England and the East Indies
were communicated to the Royal Society. 55 He
drew up instructions for an observer in Madras, no
doubt at Fort St. George, to take the temperature
of wells. To become "better acquainted with the
nature of those extraordinary phenomena," the
typhoons, he wanted everything about the weather
recorded while the storms were in progress. He
wanted barometer readings made with a vernier
scale to l/l()()th of an inch and frequent corrections
made of the height of the mercury in the cistern. I le
told the correspondent to remove his thermometer
from under a shady tree, since evaporation from
the leaves could cool it, as Cavendish had decided
by observations of his own. Finally, he had heard
that in Madras the usual way of cooling water was
by placing it in porous earthen vessels, and he
wanted his correspondent to try the method, as
Cavendish had done. 5 '' Among his papers, in his
own hand, is a copy of a weather journal from

Madras in 1777-78. 57 To nearly the end of his life.
Cavendish received observations from East Indian
companymen. 5 * Whatever may be the larger legacy
of the East India Company, it provided considerable
opportunity for British science and to its gate-
keeper in London in the 1770s and 1780s, Henry
Cavendish. India might even be seen to have
worked its spell on Cavendish as it did on many of
his country men for another century and a half: one
of his last papers was about the civil year of the
Hindoos. This seemingly exotic irrelevance in the
regular scientific concerns of Cavendish had its
roots, in part, in the East India Company and its
collaborations with the Royal Society of London.

Beginning in 1773 Cavendish incorporated
the Hudson's Bay Company into his network of
sources of an extended knowledge of the earth. Its
northern remoteness offered Cavendish and science
another and longer-lasting opportunity to study a
cold climate after Phippss voyage to the north. The

^-Cavendish. "To Make the Same Observations on the Flat lee."
"Phipps, Voyage, ZZ9.

M The expedition reached HO decree latitude before
encountering ice, sinee it made was during Rood weather. It did not
reach the pole, hut if the pole were reachable by sea. Phipps said,
the time would be after the solstice. Phipps, Voyage, 76.

"Robert Barker, "An Account of Some Thermometrieal
Observations Made at Allahabad in the East-Indies, in I, at. 25
Degrees M) Minutes N. During the Y 1767, and Also During a
Voyage from Madras to England in the Y 1774. Extracted from the
Original Journal by Henry Cavendish," PT 65 (177.5): 202-6.
Alexander Dalrymple, "Journal of a Voyage to the East Indies, in the
Ship Grenville, Capt. Burnet Abercrombie. in the Year 1775."
Communicated by the Hon. Henry Cavendish, PT 68 (1778):
.sKO— 118. Dalrymple took measurements with thermometers and
barometers made by Nairne and Blunt, and he made observations
with a dipping needle, and in his report of them gave a long extract
on the instrument by Cavendish (p. 390).

v 'Thesc directions are in a draft of a letter to a person who has a
"correspondent" in Madras. They are combined in the same
manuscript with Cavendish's directions to Phipps on observing ice.
Cavendish Mss. Misc. "Evaporation in Glazed and Unglazed Pans.
Freezing Point of Pump & Rain Water Boiled and Unboiled."
Cavendish Mss 111(a), 12. This 22-page manuscript is wrapped in a
notice to Cavendish of a meeting of the Royal Society's paper
committee in 1775.

'""Journal of Weather at Madras," Cavendish Mss. Misc.

'"James Horsburgh, captain of an Hast Indiaman, was
introduced by Dalrymple to Cavendish in 1801. From Bombay, in
1805, Horsburgh sent a paper on meteorological readings to
Cavendish to be read ar the Royal Society. It was published,
"Abstract of Observations on a Diurnal Variation of the Barometer
between the Tropics," PT 95 (1805): 177-85. Dalry mple wrote to
Horsborgh on 14 Sep. 1805 that he was going to propose to
Cavendish. Maskelyne. and Aubcrt that they join him in
recommending Horsborgh for Fellow of the Royal Society. It was
done, as Dalrymple planned it, only Aubcrt did not sign the
certificate as he died that year. Howard T. Fry, Alexander Dalrymple
(1737—1808) and the Expansion of British Trade (London: Frank Cass,
1970), 253-55. Royal Society, Certificates, 6 (2 1 Nov. 1805).

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Learned Organizations

205

connection again was the Royal Society. Hudson's
Bay had just sent the Society a valuable collection of
natural history specimens, 59 and in gratitude, of a sort,
for this and other gifts, the Society sent the company
a collection of meteorological instruments with in-
structions for its officers to measure the weather and
report back, to the Society. 60 What the Royal Society
council had in mind is suggested by a letter from
the secretary Matthew Maty to Cavendish three-
days after the council's motion. Maty acknowledged
Cavendish's "hints" about the observations to be made
at Hudson's Bay and asked where the instruments
were to be placed in that frozen climate. Because
the rain gauge, in particular, could only be used in
summer, Maskelyne had proposed that the snow
be collected on the frozen river, and Maty wanted
to know what Cavendish thought about it all. 61

From the outposts of science, Cavendish
collected facts upon which a theory of the climates
of the world could be based. He held out con-
siderable hope for the method of the heat of wells
and springs for measuring the mean heats of
climates, and in connection with that method he
wanted to test if the earth at some depth below the
surface was permanently frozen/' 2 He took the
temperature on mountains and in the upper
atmosphere, making use of a new kind of voyage,
the manned balloon, a vertical outpost of his
science. He encouraged the taking of the
temperature of the sea, as we have noted. He
calculated the time of the day when the heat of the
air is equal to the mean heat/ 1 ' and he calculated
the heat at different latitudes of the earth assuming
the sun is the source of the heat. 64 But for the most
part, he could contribute only to the methods of
meteorology, not to a general theory. For what he
could do, he depended on the Royal Society and
its connections with observers in far-away places
and on accounts of travels, often published by
other scientific societies.

One of Cavendish's few close friends in the
Royal Society was a professional voyager, the first
hydrographer for the Fast India Company and later
the first such for the admiralty, Alexander
Dalrymple. A man of great energy and versatility,
he was an explorer, chart-maker, navigator,
surveyor, commander, geographer, visionary of
commercial expansion, policy maker, author of the
first English book on nautical surveying, and moving
spirit behind the "second British Flmpire." 65

Thoroughly scientific in his approach to oceanic-
exploration, he had a keen interest in scientific instru-
ments, indeed an obsession with chronometers.
Although Dalrymple encouraged disappointed hopes
in a southern continent and in a Northwest Passage,
the voyages that disproved him made valuable
scientific observations all the same. Dalrymple was
a difficult person: Aubert got along well with him, 66
Blagden not well, and many not at all. Cavendish,
who was always greeted warmly by Dalrymple in
letters to him, had a good opinion of Dalrymple's
character, naming him a trustee of his property,
leaving him a legacy in his will, and repeatedly
lending him money. 67 Cavendish no doubt thought
he was amply rewarded in the news of the world
Dalrymple regularly brought him.

British Museum

Henry Cavendish joined his father as a
trustee of the British Museum in 1773, when he
was elected to succeed Lord Lyttleton. For ten
years he came to the biweekly meetings of the
standing committee of the trustees with his father.

v 'Thc Society's committee of natural history reported on its
examination of this collection (and another from another distant
outpost. Cape of Good Hope): Royal Society, Minutes of Council.
6:208 (20 Jan. 1774).

M Royal Society, Minutes of Council, 6:206 and 208 (23 Dec.
1773 and 20 Jan. 1774).

M Matthew Maty to Henrv Cavendish, 26 Dec. 1773, Cavendish
Mss X(b), 2.

'• 2 He put this suspicion as a "Qucre" in the draft of his sections
of the Royal Society committee report on the fixed points of
thermometers: "Whether the earth at considerable depths below the
surface is constantly fro/en or what comes to the same thing do they
if they dig into the ground at the end of summer find the ground
frozen & if they do at what depth they find it so. If they do not &
they have any wells to observe the heat of the water in them at the
end of summer & also at the end of winter & if they have any deep
cellars to find the heat of the air or ground ; n them at the same
time." Cavendish Mss. 1 1 1(a), 3.

M Henry Cavendish. "Comput. at What Time Day Heat Is
Equal to Mean Heat." Cavendish Mss, Misc.

M Henry Cavendish, "Comput. Heat in Diff. Parts of Earth,"
Cavendish Mss, Misc.

M W. A. Spray. "Alexander Dalrymple, I lydrographer," American
Septune 30 (1970): 200-216, on 200-1. Fry, Alexander Dalrymple,
xiii— xvi, xx-xxi.

""So valuable a friend," Alexander Aubert said of Dalrymple, in
a letter to Joseph Banks, 28 Sept. 1 785, BL Add Mss 33978, no, 35.

'■'Cavendish loaned Dalrymple 500 pounds in each of several
years, 1783, 1799, 1800, and 1807. Dalrymple borrowed from
Cavendish to pay off other debts due immediately: Alexander
Dalrymple to Henry Cavendish, 2 July 1807. Upon Dalrymple's
death, his administrator asked Cavendish for the amount owed him.
which Cavendish provided. The matter was still pending a few years
later when Cavendish died. "27 Dec. 1811 Principal Money and
Interest This Day Received of Alex. Dalrymple Esq. Kxctr.
2873.3.5." Devon. Coll., L/31/64 and 34/64.

206

Cavendish

Their commitment was substantial and unusual,
since rarely as many as six trustees attended these
meetings. The committee prepared reports for
consideration at the general meetings of the
trustees, which were held three or four times a
year, and rarely were there a dozen in attendance at
these, often not enough for a quorum. In addition
to the Cavendishes, the few other trustees who
attended frequently included their friends from
the Royal Society and their relatives: Banks, Wrav,
Watson, Pringle, Yorke (now Lord Hardwicke), and
Lord Bessborough.'' K

The standing committee had a wide range
of responsibilities. It paid bills, made audits, and so
on, but in much of its routine business there was
great variety. The committee gave permission for
visitors to copy documents and draw birds but also
to examine human monsters under the inspection
of an officer of the Museum. It heard complaints
about the cold of the medals room and the damp of
the reading room but also about the in-fighting of
the several librarians (the committee ordered them
to stop quarreling and be amicable'' 9 ). It laid out
money to buy or to subscribe to important works of
science for the library, such as Robert Smith's
System of Oprirks and Samuel Horsley's edition of
Newton's works. 7 " It noted gifts of books and
collectibles. No sooner had Henry Cavendish been
elected a trustee than the committee ordered
thanks to John Walsh and John Hunter for two
specimens of the electric eel, 71 and two years later
Walsh presented an electric eel the organs of which
had been laid open by Hunter, and Hunter
presented a transverse section of an electric eel. 72
Some gifts received by the British Museum were
substantial; e.g., in 1773, Banks presented his large
collection of Icelandic sagas, and Rockingham
presented his large collection of animals preserved
in spirit (in seventy-two glasses, to which he added
seventeen more glasses the next year). Most gifts
were isolated curiosities of the sort that were
written about in the Philosophical Transactions, a six-
legged pig, a frog preserved in amber, and the head
of a sea horse. Stuffed birds from the Cape of Good
I lope, serpents from the Last Indies, shells from
Labrador, insects from Jamaica, a gun and powder
horn from Bengal, Captain Cook's artificial
curiosities from the South Sea islands, and much
else from Britain's colonial extremities piled up in
the British Museum."

First Lord Charles Cavendish, then Lord
Charles and Henry Cavendish together, and then
Henry Cavendish gave conscientious attention to
the affairs of the British Museum for over fifty
years. This central, public institution for books and
collections expressed their interest in public
service and learning.

Society of Antiquaries

In the same year that he became a trustee
of the British Museum, 1773, Cavendish was
elected a Fellow of the Society of Antiquaries of
London. He was recommended by Heberden,
Wray, Burrow, Josiah Colebrook, Daines Barring-
ton, and Jean Louis Petit, all of whom were
members too of the Royal Society. 74 Macclesfield,
Birch, Banks, and other friends of Cavendish from
the Royal Society were also members of the Society
of Antiquaries, and in general the membership of
the two societies had a large overlap. 75

The Society, which originated with a group
who met in a coffee house to discuss history and
genealogy, was formally created, or re-created, in
1717. The leading spirit of the Society in its early
years was the physician William Stukeley, an
accomplished antiquarian, the "Archdruid of this
age," 7 '' who was also a prominent member of the
Royal Society. Early on, there was an attempt to
merge the Antiquarian Society and the Royal
Society, but the stronger desire was for separate-
ness and equality. In 1751 Martin Folkes, who was

'■"Henry Cavendish was elected trustee on 8 Dee. 1773. His
record of attendance is recorded in the minutes of the British
Museum: Committee, vols. 5 to 9; General Meeting, sols. 3 to 5.

''''The order for amicable personal relations was made on 9 May
1777. British Museum committee minutes.

'"Committee meetings on 31 July and 1 1 Sept. 1778, in vol. 6.

■'Committee meeting on 23 Apr. 1773, vol. 5.

"Walsh's gift was in Jan. or Feb. 1775, and Hunter's was on 16
June 1775: "Diary and Occurrence-Hook of the British Museum."

"Gifts during the first ten years of Henry Cavendish's tenure as
trustee are listed in "Diary & Occurrence-Book of the British
Museum, Ap. 2nd 1773 to April 1782 (Signed Dan. Soiander)." BL
Add Mss 45875.

"Cavendish was proposed on 21 Jan. 1773 and elected on 25
Feb. 1773. Society of Antiquaries, Minute Book 12: 53. 580.

"Of the twenty-one members of the council of the Society of
Antiquaries in 1760. eleven were also Fellows of the Royal Society,
and among its ordinary membership, there were forty-four more
Fellows "A List of the Society of Antiquaries of London, April 23,
MDCCLX." BL. F.gcrton 2381, ff. 172-75.

"•"William Stukeley. Ml).," in William Munk. The Roll of the
Royal College of Physicians of London. Comprising Biographical Sketches of
All the Eminent Physicians Whose Names Are Recorded in the Annals, 4
vols. (London, 1878), 2:71-74, on 74.

Learned Organizations

207

at this same time the president of the Society of
Antiquaries and the president of the Royal Society,
pushed through a reform, establishing a council
and officers for the Society of Antiquaries in exact
imitation of those for the Royal Society, and in that
year the Society was granted a royal charter. 77 In
other ways too it imitated the Royal Society,
acquiring a dining club, a journal, and a committee
of papers. Fellows of the Royal Society, it would
seem, sometimes acted in concert in the politics of
the other society. 78 Of the officers and council
members of the Society of Antiquaries, an undue
proportion were also Fellows of the Royal Society,
who were often not the most productive scholars of
antiquities. In an age so wondering of natural
science, there was a distinct disadvantage in being
merely an antiquary 79

At the time the Society of Antiquaries
received its charter, a member wishing to make
public new discoveries in antiquities might
consider doing it through either the Royal Society
or the Society of Antiquaries. 80 Even though the
goal of the Royal Society was understood to be the
"advancement of natural knowledge," just which
topics were considered to belong to it and which to
the antiquaries was unclear. 81 The duty of the
Society of Antiquaries was uncontroversial: to record
and where possible to collect "monuments," such
as cities, roads, churches, statues, tombs, utensils,
medals, deeds, letters, and whatever other ruins
and writings supported the "History of British
Antiquity's." 82 But just what was to be made of
such objects and documents was a matter of
judgment and strong feeling. By the time
Cavendish joined the Society, its minutes recorded
long papers, which reveal contemporary views on
the direction of the field. There was, for instance, a
paper on the history of Manchester, written on a
"rational plan," which promised to rise above the
parochialism of town histories to illuminate the
general period in the entire kingdom and to lay
open the causes of events. Antiquaries could
already condemn antiquarianism in the later
pejorative meaning of the term. 8:1 Other papers
from this time made a moral point: a history of
cockfighting corrected the errors of the modern
writers, but its purpose was to show the perversion
of cockfighting from a religious and political
institution for instilling valor to the present-day
pastime founded on cruelty, a disgrace to humanity. 84

In 1770 the Society of Antiquaries
introduced its own journal, the Atrheo/ogia, which
was the occasion for a clear and forceful statement
of the purpose of the Society. In the first volume of
the journal, the director, Richard Gough, pointed
out how things used to be done and how things
were now done differently and better. At his own
expense, Martin Folkes had published his Tables of
English Coins, giving copies to some members. That
was before the charter of 1751, which made the
Society "a more respectable body," and according
to which the Society moved to eliminate the
remaining differences between it and the Royal
Society: from then on, the council of the Society of
Antiquaries, like that of the Royal Society, was
empowered to print papers read before it, for
which purpose the council constituted itself a
standing committee. The chartered antiquaries had
as their object not their "own entertainment" but
the communication of their "researches to the
public." Like science, antiquities had a duty to the
public. Antiquaries belonged to the modern "age
wherein every part of science is advancing to
perfection." The proper use of antiquarian facts
was "history" which was not a poetic narration but

"Joan Kvans, A History of the Society of Antiquaries (Oxford:
Oxford University Press, 1956), 442.

'"Peter Davall to Thomas Birch, 22 Apr. 1754. Bl. Add Mss
4304, vol. 5, p. 126. Daniel Wray to Thomas Birth, 7 Mar. 1753, BL
Add Mss 4322, f. 1 1 1 .

7, "You must know I am a great Antiquary." a correspondent of
Thomas Birch wrote, "though I make no words of it; as half ashamed
of my taste; like a man who has taken an odd fancy to an ugly
mistress." W. Gloucester to Thomas Birch, 25 Oct. 1763, in John
Nichols. Illustrations of the Literary History of the Eighteenth Century, H
vols. (London, 1817-58) 2:144-45, on 145.

""Francis Drake told Charles Lyttleton (future president of the
Society of Antiquaries) that he had had hetter success
communicating discoveries of antiquities to the Royal Society than
to the Society of Antiquaries and that he was inclined to do the same
with his present subject, a Roman alter (which he did. publishing on
it in the Philosophical Transactions). Francis Drake to Charles
Lyttleton, 26 Jan. 1756, "Correspondence of C. Lyttleton." BL,
Stowe Mss 753, ff. 288-89.

"'James Burrow prepared a paper for the Society of Antiquaries
and "never entertained the least thought of communicating it to the
Royal Society." The Royal Society's committee of papers, however,
changed his mind; it sent his paper to the secretary of the Royal
Society, having drawn red lines through the passages directed
expressly to the Society of Antiquaries. James Burrow to Thomas
Birch, 18 June 1762, Birch Corr., BL Add Mss 4301, vol. 2, p. 363.

"-In Stukclcy's hand, in the first minute book of the Society,
([noted in Fvans, History, 58.

8J The author of "The History of Manchester" was John
VVhitaker, an Oxford fellow. In Society of Antiquaries. Minute Book
11: entry for 6 Dec. 1770.

HJ Samuel Pegge, "A Memoir on Cockfighting . . .," in Society of
Antiquaries, Minute Book 1 1: entries for 12 and 19 Mar. 1772.

208

a scientific, "regular" inquiry into the records and
proofs of the past. 85

Apart from their common cause, "science,"
"knowledge, "and "truth," and their common
membership, the Society of Antiquaries and the
Royal Society had a common work. Because science-
had its own antiquities, both societies had a concern
with the history and biography of science.* 6 History
and natural history were both collecting activities. 87
Between history and astronomy, both dating activ ities,
there was a lively interaction. 88 Antiquaries were
greatly interested in views of Pompeii and the like,
and there was now a great interest in the Gothic as
well as in the Classic, but there was also an interest
in contemporary history, so strongly marked by
science and technology, such as in the history of
the Royal Society of Arts, to which Lord Charles
and I lenry Cavendish belonged. 89

Henry Cavendish became a member of the
Society of Antiquaries at a time when the
membership w as rapidly expanding, hav ing nearly
doubled in the ten years before his election.'" 1 The
Society was becoming fashionable: many of the
new members came from the upper classes
including the nobility. A good number came from
science too: in the same year as Cavendish,
Benjamin Franklin and John Pringle were elected.
There is the suggestion that the prosperous and
the learned entered the Society to receive its new
journal, Archeologia ! n That may well have been the
case w ith Cavendish, who became a member three
years after the journal was founded, for we know-
that he was interested in the contents of the
journal. Many Fellows of the Royal Society
published in the antiquaries' journal, among them
those who recommended Cavendish for Fellow of
the Society of Antiquaries, Barrington, Colebrooke,
and Wray. Cavendish took particular interest in
papers in Arcfieo/ogia having to do with India; his
own paper on the Hindoo calendar fitted either
that journal or the Philosophical Transactions, which
was where he published it.

Henry Cavendish's membership in the
Society of Antiquaries together with that in the
Royal Society and his trusteeship in the British
Museum were inscribed on the plate of his coffin,
but to Cavendish the affiliations were not of
comparable importance. He dedicated himself to
the affairs of the Royal Society and the British
Museum, whereas he took on no responsibilities in

Cavendish

the Society of Antiquaries. He entered the record
only once and then as an intermediary, submitting
drawings of an Indian pagoda in the name of his
scientific friend Alexander Dalrymple. ,)J

There had been a plan to bring together in
the same meeting place the Society of Antiquaries,
the Royal Society, the British Museum, and the
Royal Academy of Fainting, Sculpture and
Architecture, but it did not come off. The British
Museum moved into Montagu House in 17S4, and
the year before the Society of Antiquaries took
over a former coffee-house in Chancery Lane.
Twenty years later, in 1773, the year Cavendish
was elected to the Society of Antiquaries, the
Royal Society began planning its apartments for its
new location, Somerset House. Cavendish was
much involved with that move, and with others on
the council of the Royal Society that year, he-
agreed that it would be a "great inconvenience" to
have any apartments in common with the Society
of Antiquaries, or even a common staircase. The
claim on all possible space was only consistent with

HS Richard Gough on the purpose of the Society of Antiquaries'
publication, in volume 1. 1770, of Archeologia.

w> There was a broad use of "science." Birch, a writer of several
biographies, received this compliment: he was said to be "curious in
Biography as well as other Branches of Science." J. Owen to Thomas
Birch, 1748. BI. Add Mss 4.516. f. 1 10. There are many letters from
members of the Royal Society to John Ward, professor of rhetoric at
Gresham College. T.R.S.. w ho published frequently on antiquities in
the Philosophical Transactions and w as also president of the Society of
Antiquaries. For example, Ward had a correspondence about
collecting the scientist Robert Boyle's letters for the benefit of the
Royal Society: Henry Miles. T.R.S., to Ward, 1(1 Teh. 1741/42 and 13
June 1746, in "Letters of Learned Men to Professor Ward," BL Add
Mss 6210, ff. 248. 249-50.

*'ln connection with a natural history of fossils, Emanuel
Mendes da Costa w rote to John Ward to ask if certain Roman vases
were made of marble or porcelain. Letter of 13 Nov. 1754, "Letters
of Learned Men to Professor Ward." BL Add Mss 6210.

"""My whole time has been employed in tedious and irksome
calculations to adjust and settle the moons mean motion, in order to
make a proper use of the eclipse at the death of Patroculus." John
Machin wrote to John Ward. Machin was concerned with Homer's
placement of 'Troy. Letter of 23 Oct. 1 745, ibid., f. 230.

"'' This "history of the rise and progress of the Society for the
Encouragement of Arts. Manufactures & Sciences" was read on the
meetings of 1 and 8 June 1758. 'The paper was kept in a folio w ith
the purpose of entering "occurrences of our own time." Emanuel
Mendez da Costa. "Minutes of the Royal Society and the Society of
Antiquaries," BL, Egerton Mss 2381, ff! 57-58.

'"'Membership was 1 73 in 1 764 and 290 in 1 774. Evans, History, 148.

»' Evans, History, 150.

'-'Henry Cavendish to William Norris, undated. This letter is in
the library of the Society of Antiquaries, and it has to do with an
extract by Alexander Dalrymple from a journal in the possession of
the Last-India Company. It evidently refers to "Account of a Curious
Pagoda Near Bombay . . .," drawn up by Captain Pyke in 1712, and
communicated to the Society of Antiquaries on 10 Feb. 1780 by
Dalrymple: published in Archeologia 1 ( 1 785): 323-32.

Copyriqluer]

Learned ( Organizations

209

the "external splendor" of the Royal Society. 95 The
Society of Antiquaries did, in fact, meet in
Somerset House from the beginning of the 1780s,'' 4
but in this vote of the council. Cavendish came
down on the side of the Royal Society.

MRoyal Society, Minutes of Council 6: 302-3(10 May 1773).

"■•William Chambers, the arehiteet, informed the Royal Society
that no space could be allotted to it consistent with its "splendor"
other than what it had in common with the Society of Antiquaries.
Royal Society, Minutes of Council 6:304-6 ( IS May 1776).

Copyrighted mawri

CHAPTER 7

Personal Life

Death of Lord Charles Cavendish

Lord Charles Cavendish was remarkably
healthy. He experienced the almost universal
malady of that time, gout, but he was not crippled
by it, 1 and to judge by his attendance at meetings,
he did not suffer from any protracted illnesses. He
attended a meeting of the standing committee of
the British Museum on 7 February 1783, 2 only a
few weeks before his death. He died "on or about"
28 April 1783; 5 by our reckoning, he was probably
seventy-nine. Not yet famous as the father of Henry
Cavendish, his obituary notice in the Gentleman's
Magazine identified him as the great uncle to the
then present duke of Devonshire, who but for his
title was a non-entity. 4

For so rich a man, Cavendish's will was
remarkably brief, as his son Henry's would be too.
Unchanged since it was made out thirty years
before, his will left to his younger son, Frederick,
the money owed him from his mother's estate ac-
cording to the marriage settlement. With the excep-
tion of a thousand pounds for charity, it left all the
rest of his estate to his oldest son and sole executor,
Henry. 5 That included real property, securities, and
the recently inherited, combined estates of the
three related Cavendishes Lord James, Richard
(Chandler), and Elizabeth/'

Writing to Henry Cavendish a month after
his father's death, John Michell apologized for
imposing on him "so soon after the loss of Ld
Charles." 7 What his death meant to Henry we can
only surmise. Henry was now fifty-two, and no one
in his life had had anything like his father's
importance for him.

Besides his wealth, Lord Charles left all of
his books and instruments to Henry, but then it
would seem that these had always been common
property. Henry made an inventory of his and his
father's papers, which were kept in the same place,
a tall walnut cabinet with an upper case, and which
he now classified as Fathers papers and Mine. The

occasion was probably Henry Cavendish's
resettlement at Clapham Common and Bedford
Square after his father's death. Like his father,
Henry kept everything, even "begging letters" and
crank science. All of the personal papers have,
evidently, been destroyed, but it was unlikely
Henry who destroyed them; rather he classified
and stored them under lock and key. Spare as it is,
Henry's inventory is an aid in understanding Lord
Charles Cavendish's life. Papers belonging to his
father that we do not have but that Henry
Cavendish did include letters to and from his
father and his family, letters to his wife, Lady
Anne, Frederick's letters, letters from abroad, 8
poetry, and genealogy. Also lost are Lord Charles
Cavendish's scientific papers, which include
measurements (probably meteorological) taken at
Chatsworth, mathematical papers, and other papers
on meteorological instruments, refracting telescopes,
crystals, artificial cold, specific gravities, and a

'Cavendish was hindered from writing by gout in his hand, he
told his steward: letter to Thomas Rev ill, 2 Mar. 1765, Devon. Coll.,
L/31/20.

2 Kntrv for 7 Hen. 1 783, British Museum, Committee Minutes,
vol. 7.

'Devon Coll., L/31/37.

4 Kntry in Gentleman's Magazine .53 (1783): 366 The notice put
Lord Charles Cavendish's age at ninety, but it got this much right: he-
was "most amiable." and he was an "excellent philosopher."

'Lord Charles Cavendish's will was probated on 28 May 1783.
"Special Probate of the Last Will and Testament of the Right IIon Mc
Charles Cavendish Esq' Commonly Called Lord Charles Cavendish
Deceased," Devon. Coll., L/69/12.

Hlpon Lord Charles Cavendish's death. Lord Camden became
the sole surviving executor of the residue of F.lizabeth Cavendish's
estate. I lenry ( Cavendish promptly applied to him, "being desirous of
having" all the wealth in his own hands. "Lord Camden and 'The
Honorable Henrv Cavendish. Assignment and Deed of Indemnity,
Dated Thirty-First of December 1783," Devon. Coll., L/31/37.

7 John Michell to Henry Cavendish, 26 May 1783. Cavendish
Mss, New Correspondence.

"Henry Cavendish lists among his father's papers the "Ruvigny
papers" and "letters from abroad." We have not looked abroad for
Charles Cavendish's letters, which the next biographers of Henry
Cavendish will no doubt want to do. These may have been treated
differently than the letters received by Charles Cavendish, which
evidently suffered the fate of nearly all sentimental records in the
Cavendish family.

212

Cavendish

pocketbook of experiments. 1 ' Papers that have
survived include legal documents having to do with
wills, annuities, titles, rents, dividends, suits, and
his marriage settlement. With a few exceptions,
Henry Cavendish's own papers in the combined
classification have to do with the same things as his
father's: properties and lawyers. 10

What direct evidence we have of Lord
Charles Cavendish's intimate life is meager. But
we know this much: he died in the knowledge that
his oldest son was in competent charge of his life
and master of his chosen line of work, science. His
son had followed his direction in life and had gone
beyond him. Of all of his achievements, the
example and assistance he gave Henry were his
greatest and, we trust, his proudest.

Whatever I Ienry Cavendish felt about his
father's death he kept to himself, as he did all
private matters. To the rest of the world, there was
one slight change, this a matter of protocol. Upon
the death of Lord Charles, Henry Cavendish's
name was no longer preceded by "Hoik" in his
publications in the Philosophical Transactions. Strictly
speaking I Ienry never had a right to the title;" "The
1 lonourable" was a courtesy title once removed, and
from 1783 on, he was Henry Cavendish "Esq." or
simply, as he always put it, H. or Henry Cavendish.

Charles Blagden

At about the time his father died, Henry
Cavendish acquired a close and lasting friend,
Charles Blagden. Given Cavendish's habits of
privacy, his willingness to allow a stranger to be
close to him is remarkable in itself.

Blagden holds an interest of his own. A man
of modest means and abilities (unlike his new
friend Cavendish in both respects), he made for
himself a life in science at a time when there was
no such profession, and his friendship with
Cavendish played a part in his plans.

Blagden received a good scientific education
in the course of his medical studies at Edinburgh
University, where he took his M.D. in 1768. While
he was there, both William Cullen and Joseph
Black lectured on chemistry, and he heard them
both. Blagden became a friend of Cullen, whom he
looked up to as his teacher; from his side, Cullen
regarded Blagden as a "friend," with whom he had
"particular intimacy," Blagden having been "very
much in my family."'- Blagden's manuscripts

contain a copy of Black's lectures, partly in his own
hand, 13 and a testimonial by Black that Blagden
attended his lectures. 14 In the year following his
graduation, Blagden set up practice in Gloucester,
where he kept an electrical machine made by Jesse
Ramsden, which he evidently used on his patients.
He acquired a good reputation in Gloucester, but
he was restless. 15 His sights were set on London
where, a friend told him, a physician like William
Heberden could earn 2,000 to 4,000 pounds a year,
maybe more. This friend also told him that he was
still too young because no one in London took
seriously a physician under thirty; he should stay in
the provinces for four or five more years.' 6 Another
friend also tried to dissuade Blagden from leaving
Oloucester, but he acknowledged that Blagden's
happiness lay in the "great town." 17 By 1772
Blagden was living in London.

In London Blagden expanded his connec-
tions with science. Elected to the Royal Society, he
carried out brave experiments in concert with a
number of other Eellows. Guided (and protected)
by a doctrine he attributed to Cullen, he tested the
power of the human body to resist high
temperatures, which became the subject of his first

'"Walnut Cabinet in Bed Chamber," "Papers in Walnut
Cabinet," and "List of Papers Classed," Cavendish Mss, Misc.
List of Papers Classed."

""The Honourable" followed by given name and surname was
allowed the sons of earls and the children of viscounts and barons.
Other than for a duke, w ho was called "His Cracc." and a marquess,
who was called "The Most Honourable," the title " The Right
Honourable" was given to all peers as a courtesy. Henry Cavendish
was none of these things. His father, however, w as sometimes called
"The Right Honourable Lord Cavendish." both parts of his title
being by courtesy and proper. Treasures from Chatsworth, The
Devonshire Inheritance. A Loan Exhibition from the Devonshire
Collection, by Permission of the Duke of Devonshire and the
Trustees of the Chatsworth Settlement, Organized and Circulated by
the International Exhibits Foundation, 1979-1980, p. 24.

'-William Cullen to William Hunter, II Feb. 1769; quoted in
John Thomson, An Account of the Life, Lectures, and Writings of William
Cullen, M l).. Professor of the Practice of Physic in the University of
Edinburgh. 2 vols. (Edinburgh, 1859) 1:555-56, on 555.

''Blagden was in Edinburgh in 1765-69. Charles Blagden to
William Cullen. 17 June 1784, draft. Vale. Blagden Letterbook.
Joseph Black's lectures are in Box 71 of the Blagden Papers at Yale.
Henry Guerlac, "Black, Joseph," DSB 2:17.V83, on 17.V74.

14 Joseph Black to Charles Blagden, 5 Oct. 1769, Blagden
Letters, Royal Society.

' ^ J - Smart to Charles Blagden, 22 Sept. 1769; Henry Cumming
to Charles Blagden. 7 Nov. 1769; Jesse Ramsden to Charles Blagden,
23 Nov. 1769; Thomas Curtis to Charles Blagden, 26 Dee. 1769 and
8 Feb. 1770. Blagden Letters, Royal Society. S.ll, C.72, R.40.
C.77. C.79.

"■Thomas Curtis to Charles Blagden. 15 Jan. 1770, Blagden
Letters, Royal Society. C.78.

17 J. Smart to Blagden. 24 Feb. 1772. Blagden Letters. Royal
Society, S.16.

Personal Life

213

paper in the Philosophical Transactions. He and his
colleagues spent considerable time inside a room
heated to temperatures above the boiling point, to
nearly 260 degrees. Eggs hardened, beefsteak
roasted, but Blagden and the other human subjects
emerged unharmed, proof, to Blagden, of the
ability of the human body to destroy heat. 18 In
1775, the year of the last of his experiments in a
heated room, Blagden made a scientific connection
with Cavendish. Now an army surgeon assigned to
go to North America, he was instructed by
Cavendish on how to serve science at the same
time: on the voyage to America he was to compare
the temperature of the sea with that of the air, and
when he got there he was to make observations of
the temperature of wells and springs. These
directions, Blagden said, "led to my discovery of
the heat of the gulf stream" and to a publication in
the Philosophical Tra nsactions Because of the war,
Blagden had little opportunity to make the
observations of wells and springs that Cavendish
wanted. Blagden followed events in science as best
he could at long distance, including its politics; he
asked Banks why Cavendish was left off the
council of the Royal Society in 1778. 20 He longed
to resume his life in science, and in 1779 he got
permission from Cornwallis to return from America
to England.

By 1780 Blagden was settled in Plymouth,
where he remained for two years, working in the
military hospital there. He was back home but he
was not in London; he was in Plymouth, which he
characterized to Joseph Banks as "miserable exile."- 1
In an ideal life, he would "live as much as I can
among books," and he asked Banks if the Royal
Society could make him "Inspector of the Library, or
something of that sort," with apartments in or next to
the Royal Society in Somerset Place. Banks said no, 22
leaving Blagden to explore other ways to escape his
exile. The North Pole voyager Phipps, by then Lord
Mulgrave, repeatedly offered his connections in the
admiralty to help Blagden's career. 2 '

In the summer of 1782 Blagden attended
lectures by an "itinerant Philosopher," Dr. Henry
Moyes, who was blind, and who was reputed to be a
prodigy, but whose knowledge of recent develop-
ments Blagden found "extremely inaccurate &
defective," 24 at best scraps from Black's lectures on
heat. Blagden scoffed at Moyes's claim that
mercury freezes at minus 350 degrees. The day

after a lecture and apparently suggested by it,
Blagden recorded in his diary "hints" for experi-
ments on heat, "ideas which suggested them-
selves": in addition to experiments, he speculated
"whether heat may not be the cause of all chemical
attracting, the different bodies not attracting one
another, but attracting the common medium,
heat. . . "25 This way of thinking about heat was
decidedly not Cavendish's, but that did not stand
in the way; Blagden was soon making experiments
on freezing mixtures, sometimes with Cavendish.

At some point Blagden moved from
Plymouth to London to live with his brother and to
make his fortune there. In early 1783 he went on
half pay as a physician to the forces. 2 ' 1 He was now
again in regular personal contact with the leading
men of science, at the Royal Society and its dining
club, at the Monday Club that met at the Ceorge
and Vulture, and at the homes of individuals,
William Herschel, Alexander Aubert, and Banks.
In the summer of 1782 Blagden began visiting the
heads of the Cavendish family, the duke and
duchess of Devonshire, often dining with them. In
March of that year, he had breakfast at their cousin
Henry Cavendish's house, and that fall he began

'"During Blagdcn's stay in Ldinburgh. "the idea of a power in
animals of generating told (that was the expression) when the heat of
the atmosphere exeeeded the proper temperature of their bodies,
was pretty generally received among the students of physic, from Dr.
Cullen's arguments." Blagden had done a simple experiment at the
time that agreed with (allien s idea. Charles Blagden, "Kxpcrimcnts
and Observations in an I leated Room." and "Further Experiments
and Observations in an Heated Room." /'7'65 (1775): 1 1 1-23, 484-94.
quote on 1 12.

'''Blagden found the gulf stream to be several degrees warmer
than the sea through which it ran. He thought that seamen ought to
take a thermometer with them as an aid to navigation. Charles
Blagden. "On the Heat of the Water in the Gulf-Stream, " PT 71
(1781): 334-44, on 334, 341-44. The full quotation is: Cavendish in
1775 "recommended an attention to the temperature of the sea, as
compared with that of the air, which led to my discovery of the heat
of the gulf stream." Draft of a paper in Blagden Papers, Vale, box 2.
folder 26.

-"Blagden wrote to Banks about science, which interested him
more than the war he was part of. He commented in the same letter
about Cav endish's view s on electricity. ( )harles Blagden to Sir Joseph
Banks, 2 Mar. 1778, copy, BM(MI), 1)1 C 3: 184.

-'Charles Blagden to Sir Joseph Banks. 3 Nov. 1782. copv,
BM(MI), D'lC 3: 205.

"Charles Blagden to Sir Joseph Banks, 19 July 1782. draft: Sir
Joseph Banks to Charles Blagden. 19 Aug. 1782. Blagden Letters,
Royal Society, B.8a and 9.

a For example, Lord Mulgrave to Charles Blagden. 1 Mar. 1780.
Blagden Letters, Royal Society, p. 35.

'■•Blagden to Banks, 19 July 1782 .

J, Kntries for 16, 18, 19 July 1782, Blagden Diary, Royal Society .
J,, Lettcr from the war office: Fit/Patrick to Charles Blagden. 7
May 1783. Blagden Letters, Royal Society, I'lO.

214

Cavendish

assisting Cavendish in experiments. In keeping
with a promise he had made to Cavendish before
he left for the war in America, Blagden collected
Plymouth air in all kinds of weather, nine bottles
worth, which he brought to Cavendish in his new
house in I lampstead as, we imagine, a kind of
house-warming present. Together they tested these
samples of air w ith the eudiometer. 27 In December,
with Cavendish, Blagden went over the experi-
ments on extreme cold done at Hudson's Bay
under Cavendish's direction, and, on "Cavendish's
advice," he set about to learn what had been done
on that subject "chiefly with a view to quicksilver," 28
w hich would lead to his published history of the
freezing of mercury the follow ing year. In his en-
thusiasm for experimenting on freezing mixtures,
he froze a finger white several times;-"' on 27 February
1783 he recorded that the day before Cavendish had
frozen mercury. By 1785 Cavendish and Blagden's
association was recognized: that year, for the first
time, Banks in letters to Blagden asked him to give
his compliments to Cavendish. Banks toasted them:
"may success attend all your mutual operations." 30
Blagden and Cavendish were both single
and resettling, Cavendish in mid life at fifty-one,
and Blagden in a change of career at thirty-four.
They had much to offer one another. Blagden was
interested in everything happening in science,
eager to be found useful by men of science. He
would give Cavendish unstintingly of his time; he
would gladly be Cavendish's scientific assistant,
secretary, eyes and ears, runner of errands, and
companion in dining, meeting, and traveling.
Blagden was knowledgeable in science, he could
handle instruments, and at the same time he was
definitely Cavendish's assistant. Blagden was a
diligent correspondent, a linguist who cultivated
connections with foreign scientists; he was eager to
serve as a go-betw een, taking pride in his know ledge
of persons and events, even of gossip. He would
soon, in 1784, be secretary of the Royal Society,
which would greatly extend his lines of
communication. In that capacity, in 1786 he wrote
to Benjamin Thompson in Germany: "It is scarcely
possible that any ph/ilosophical/ discoveries can be
made in England without coming to my knowledge
by some channel or another." 31 With his extensive
foreign connections, he could have said nearly the
same about his knowledge of philosophical
discoveries abroad. Blagden took on editorial work

for the Philosophical Transactions, and privately he
did the same for Cavendish's papers published in
that journal. 3 -' Blagden was boundlessly curious
about the world, had an excellent memory, was a
man of facts, and was reliable and loyal and always
accessible when Cavendish had need for him." It
would be hard to invent a man better suited than
Blagden to be Cavendish's right hand. What Blagden
expected in return for his services to Cavendish is
less clear. Some favors were simply mutual; Blagden
could ask Cavendish to go to his house to look for
things for him, 34 just as it worked the other way
around. Cavendish supplied Blagden with any scienti-
fic information he wanted: on claims for a barometric
rube made by George Adams, Blagden was skeptical
but unsure: "but Mr Cavendish will be here presently,
& then I will consult Aim." 35 Blagden's papers
contain many letters from Cavendish on questions
of science pertaining to Blagden's interests. 36

During a stretch of Cavendish's most pro-
ductive years, Blagden was closer to him than
anyone else. Blagden assisted Cavendish in his
researches, but then so did Cav endish assist him. Of
ten papers Blagden published in the Philosophical
Transactions, four originated with Cavendish and
two others were done with Cavendish's help. 37

-'Charles Blagden to Sir Joseph Banks, 3 Nov. 1782, copy,
BM(NH), DTC 3: 205. Kntry for 28 Nov. 1782. Blagden Diary. Royal
Society.

"Entries for 17 and 23 Dec. 17X2. Blagden Diary, Royal Society.

-"'Kntry for 25 Feb. 1783, Blagden Diary, Royal Society. There
arc many other entries on this subject around this time.

"Sir Joseph Banks to Charles Blagden, 2X July and 4 Aug. 1785.
Blagden Letters. Royal Society, B.35 and 36.

''Charles Blagden to Benjamin Thompson, 7 Feb. 1786, draft,
Blagden Letterbook, Yale.

'-Blagden made changes in Cavendish's papers in manuscript
and read and corrected their proofs. He always showed Cavendish the
changes he made. In connection with Cavendish's paper on gases in
1785. for example, he sent Cavendish not only the revised proofs but
the first proofs too so that Cavendish "may the more readily perceive
some alterations which 1 thought it expedient to make." Charles
Blagden to 1 lenry Cavendish, n.d. /1 785/, Cavendish Mss X(b), 4.

''Blagden told Cavendish he would be home that evening
should Cavendish have any questions. Charles Blagden to Henry
Cavendish, n.d. /1784 or 1785/, Cavendish Mss, New Correspondence.

''Charles Blagden to Henry Cavendish, lb Sept. 1787,
Cavendish Mss X(b). 13.

"Charles Blagden to Sir Joseph Banks. 12 Oct. 1786. BL Add
Mss 33272, pp. l l J-20.

"•These < )avendish letters are in the Blagden Papers, Royal Society.

"In the ten papers. I omit two by Blagden in the Philosophical
Transaction?, an extract from a letter by Blagden on the tides at Naples
in 1 7 U 3. and an appendix to Ware's paper on vision in 1813. The repeated
involvement of Cavendish in Blagden's scientific work is documented
in Blagden's papers, both by what he writes and by the many sheets
in Cavendish's handwriting intermixed with his. Blagden Papers.
Yale, box 2. and elsew here.

Capyr

Personal Life

2/5

Blagden considered establishing a medical
practice in London, but he lacked the desire or
drive. He needed income, and it has been assumed
that Cavendish answered his need. Given the
social and financial mismatch of Cavendish and
Blagden, the rumor mills were busy: the chemist
Kirwan, who had a wicked pen, told a French
colleague that Blagden only looked through Cav-
endish's telescope because Cavendish "is a near
relation of the duke of Devonshire and has six
thousand pounds sterling yearly income." 38 Caven-
dish is said to have settled an annuity of 500
pounds on Blagden, but we wonder if that is true. 39

Blagden was drawn to persons of rank and
of accomplishment and, in particular, to Cavendish
who had both. Blagden kept an eye out for
patronage, always, since that was how a person like
himself advanced. Cavendish offered Blagden
patronage but it was probably not financial, though
Blagden probably calculated on that too one day.
By placing his trust publicly in Blagden, Cavendish
helped Blagden to realize a place in the world.
Through Cavendish, Blagden had a small part in
the great scientific developments of his time. In
serving Cavendish, Blagden served a cause he
believed in; what may sound like mutual
exploitation is better described as mutual benefit
and convenience. Their friendship probably was
not that cold either, though the nature of it is
elusive, as both men were reserved. Both lived by
strict routines but were able to accommodate their
routines to one another's; to what degree personal
warmth made this possible, we can only wonder.
When Blagden heard that Cavendish had died, he
wrote in his diary that day, "felt much affected." 40

The relationship between Blagden and
Cavendish is said to have ended with a formal
break, in 1 789. 41 The break at that time, as we will
see, was in the first instance not a break between
Blagden and Cavendish but one between Blagden
and Banks. After 1788 neither of them published
any more experimental researches (with the excep-
tion ten years later of Cavendish's weighing of the
world), but they continued to meet to perform
experiments at Clapham Common, 4 - and Blagden
continued to dine at Cavendish's house. 43 When
Blagden was out of the country, he continued to
write to Cavendish with scientific news. 44 When
Blagden wanted support in the Royal Society,
Cavendish gave it, as in 1793 when Blagden wanted

to stay abroad another year and retain his
secretaryship in the Royal Society. 45 And when
Blagden fell ill while abroad, he had his doctor
inform Cavendish, who in turn informed Banks. 4 ''
Blagden would be known as an "intimate friend"
of Cavendish. 47 The change in their friendship was
one of degree not of kind, and as long as Blagden was
in London he and Cavendish continued to meet
regularly to the end of Cavendish's life. When
Cavendish died, Blagden spoke of an earlier time-
when he was "intimate with him." 48

In all of the correspondence we have seen,
Blagden never said a word against Cavendish, as he
did freely against persons who slighted him.
Whatever their understanding had been, if it had
ever been spelled out, Cavendish had treated
Blagden justly by it, and Blagden never disappointed

'"Richard Kirwan to Guyton dc Morveau, 9 Jan. 1786, in A
Scientific Correspondence During the Chemical Revolution: Louis-Hernard
Guyton de Morveau and Richard Kirwan, 1182-1802 ed. E. Orison, M.
Sadoun-Goupil and P. Bret (Berkeley: Office for History of Science
and Technology, University of California at Berkeley. 1994), 161-64,
on 163.

w Lord Brougham, Lives of Men of Science, first series, pp. 445-46,
cited in George Wilson, The Life of the Honourable Henry Cavendish
(London, 1851), 133. There may have been such an annuity, but the
evidence we have so far uncovered does not reveal it. In fairness to
the rumor of a 500-pound annuity, however, we note that Blagden's
income in 1785/86 was 511 pounds (he was in debt, since he paid out
726 pounds in the same time): Gloucester Record Office, I) 1086, F
158. Blagden held securities, and he had a salary from the Royal
Society. In the bundle of Blagden's papers labeled "Accounts. Bills.
Insurance, and Copy of Will of S. Nelmes," we find that as executor
and beneficiary of the will of his distant relative Sarah Nelmes,
Blagden received over 2000 pounds in 1777, but there is no mention
of Cavendish: Blagden Manuscripts, Royal Society. In Blagden's
household records, we find two or three references to Cavendish but
none to any income from Cavendish: Gloucestershire Record Office.
D 1086. The Cavendish scientific and estate papers at Chatsworth
do not refer to it either.

*>Entry for 24 Feb. 1810, Blagden Diary, Royal Society.

41 Wilson, Cavendish, 129.

42 Charlcs Blagden to Henry Cavendish, 5 Oct. 1790, draft,
Blagden Letterbook, Royal Society, 7.702.

'Charles Blagden to Captain Stirling, 4 Apr. 1791, draft,
Blagden Letterbook, Royal Society, 7.51 1.

"Blagden told Banks to tell Cavendish to expect a letter from
him on an excursion to Tivoli. Charles Blagden to Sir Joseph Banks,
1 1 May 1793, BL Add Mss 35272.

♦'Sir Joseph Banks to Charles Blagden, n.d. /after 11 May 1793/,
draft, BL Add Mss 33272, p. 121.

^Cavendish had been informed of Blagden's illness a week
before, but he did not tell Banks until he had something "more
precise." Cavendish described the violent fever but reassured Banks
that now there was the "utmost reason" to expect Blagden to
recover. He was receiving the "utmost care." and his "head was
perfectly clear." Henry Cavendish to Sir Joseph Banks, 23 Sept.
1793, copy, BM(NH), DTC 3:257.

■"Lord Castlcrcagh to Sir Charles Stuart in the foreign office, 13
July 1819, copy, Blagden Letters, Royal Society, C6.

4 "Entry for 1 Mar. 1810, Blagden Diary, Royal Society, 5:back
p. 428.

216

Cavendish

Cavendish in any important matter. It might seem
odd that more cannot be said about the personal
aspect of this unique friendship of Cavendish,
since Blagden was a diarist, an untiring cor-
respondent, and a fluid conversationalist. (He was
known for his "copiousness and precision,"
Boswell said, and Johnson regarded Blagden as a
"delightful fellow." 4 '' Lord Glenbervie found him
"conceited and pedantic." 50 No one, however,
accused him of ever being at a loss for words.)
Blagden had an opportunity to see Cavendish on a
daily, intimate basis for years on end. He might be
expected to have left a personal account, since,
after all. Cavendish was famous both as a great
scientist and as an extremely eccentric character.
The explanation may lie in a remark by Blagden on
Boswell's account of his and Johnson's tour of the
Hebrides: "Most people would be sorry to have a
bosom friend, who kept a journal of their
conversations, to publish as soon as they should be-
dead. " 5I On principle, it would seem, Blagden did
not become Cavendish's "Boswell." Nonetheless,
it is from Blagden's letters and diary that we know
much of what we do about Cavendish's life from
the mid 17K()s to the end. Perhaps not too much is
lost because of Blagden's reserve, since Cavendish
kept his thoughts about life to himself, and there
were plenty of others who were glad to repeat
anecdotes about Cavendish.

Monday (Hub

The setting of Henry Cavendish's social life
was clubs. From the Restoration in the
seventeenth century through the eighteenth
century and beyond, men of science congregated
in the coffee houses of London, 52 where they
drank, ate, smoked, talked, and did experiments. 53
The Royal Society Club was the best known and is
the best documented of Cavendish's clubs, but
from letters to Cavendish and from Blagden's diary
we know of other, less formal clubs, which kept no
records. Clubs commonly went by the names of
the coffee houses and taverns where their meetings
took place, which is how we know Cavendish's.
The earliest reference occurs in letters by
Alexander Dalrymple, who sent greetings through
Cavendish to their mutual friends at the Mitre and
at the King's Head. The King's Head Tavern in
Chancery Lane was where Robert Hooke and

other Fellows of the Royal Society gathered in the
late seventeenth century; but King's Head was one
of the commonest names for taverns. 54 The Royal
Society Club met at the Mitre Tavern on Fleet Street,
and later at the Crown & Anchor on the Strand. In
the 1780s, in letters to Cavendish, John Michell
repeatedly greeted their common friends at the
Royal Society and at the Cat and Bagpipes. This
latter sign is more original, but about all that is
known is that the tavern was located on Downing
Street and was popular. 55 There were many other
scientific clubs, not always neatly separable.
Cavendish did not belong to the club that met at the
Chapter Coffee House and later at the Baptist Head
Coffee House, even though persons he saw regularly
such as Aubert, Nairne, and Kirwan belonged to it. 56
Nor did he belong to another club that met at Jack's
Coffee House and later at Young Slaughter's Coffee
House on St. Martin's Lane, though Blagden, Banks,
Keir, Maskelyne, Ramsden, Smeaton, Schuckburgh,
Phipps, and Cook, among others Cavendish knew,
went there. 57 Other groups of scientific men met in
houses; one, for example, met on Saturday even-
ings at Banks's, 5 * another at Kirwan 's. 59

♦'Quoted in Frederick H. German, "Sir Charles Blagden,
F.R.S.," Osiris 3 ( 1937): 69-87. on 73.

""Lord Glenbervie, Diaries (London, 1928), quoted in a footnote
in The Diary of Sir Charles Blagden," ed. (>. R. De Beer, Notes and
Records of the Royal Society of London 8 ( 1950): 65-89, on 76.

"'Charles Blagden to Joseph Banks. 9 Oct. 1785. Banks
Correspondence, Kew, 1.210.

"A. K. Musson and E. Robinson, Science mid Technology in the
Industrial Revolution (Toronto: University of Toronto I'ress. 1969), 58.

"'Bryant Lillywhite, London Coffee Houses. A Reference Hook of
Coffee Houses of the Seventeenth, Eighteenth and Nineteenth Centuries
(London: George Allen & I nwin. 196.?). 22-24. Joseph Banks
described an unsuccessful experiment tried before the Royal Society
Club at the Crown and Anchor: letter to Charles Blagden, 28 Sept.
1782. Royal Society. Blagden Letters, BIO.

M Henry Lyons. The Row/ Society. 1600-1940: A History of Its
Administration under Its Charters (New York: Greenwood, 1968), 171.
Many, seven. King's 1 lead tav erns are lisred under signs of taverns in
the Vade Mecum, and included in Walter Besanr, London in the
Eighteenth Century (London: Adean & Charles Black. 1902). 639-40.

"" That much is known about the tavern, from Notes and Queries,
9 Nov. 1850, p. 597. quoted in Archibald Gcikic. Memoir of John
Michell (( lambridge: Cambridge I niversity Press, 1918). 58.

s,, This club usually met twice a month. Its membership was about
two dozen, and it was more formal than many of the associations then,
keeping a minute book, of which there is a copy in the Museum of
Science. Oxford. G. L'E. Turner, "The Auction Sales of the Karl of
Bute's Instruments, 1 793," Annals of Science 23 ( 1 967): 2 1 3-42, on 220.

"Henry B. Wheatley, London. Past and Present. A Dictionary of Its
History. Associations, and Traditions, 5 vols. (London. 1891), 2:484.
Lillyw hite. London Coffee Houses. 404.

""John Strange to Joseph Banks. 8 Aug. 1788, Banks
Correspondence, Kew. I. 515.

s ''Musson and Robinson, Science and Technology in the Industrial
Revolution, 123.

Personal Life

217

Besides the Royal Society Club, we know
about only one other club to which Cavendish
belonged, the Monday Club, named after the day
of the week it met. The place was the George &
Vulture, a coffee house located in George Yard, off
Lombard Street. 60 This long-lived club went back
at least to the 1760s,'' 1 and Cavendish came
regularly to it for fifteen years or more. When John
Pringle returned from Edinburgh to London in
1781, he rejoined the Monday Club, where he met
with "such friends as Mr. Cavendish, Dr.
Heberden, and Dr. Watson." 62 He also met with
Blagden, who began coming to the Monday Club
almost immediately after returning to London, as
we know from his London diary. w Aubert,
Dalrymple, and Franklin were also members, all
friends of Cavendish. 64 The discussions at this club
were, in part, continuous with those at the Royal
Society and the Royal Society Club. For example:
Aubert, who belonged to this club too, wrote to
Herschel about a paper by the St. Petersburg
academician Anders Johan Lexell (no doubt about
Herschel's "comet" of 1781, which Lexell deter-
mined was not a comet but a new planet, Uranus),
which he intended to communicate to the
members of both the Royal Society and the
Monday Club. 65 For another example: in 1789
Aubert read a paper by Peter Dolland to the
Monday Club, who at that meeting consisted of
Cavendish along with Blagden, Phipps, Nairne,
Smeaton, John Hunter, and two others. The paper

had to do with a disagreement between Dolland
and his fellow instrument-maker Ramsden, and
upon hearing the paper, the Monday Club agreed
that it was temperate and clarifying, and as a result
Aubert wrote to Banks to recommend that
Dolland's paper be read at the Royal Society. 66
Blagden's diary reveals that through the mid 1790s,
he and Cavendish often went together to dine at
the Monday Club. Upon coming home from the
George & Vulture one Monday night, Blagden
wrote in his diary: "went with him /Cavendish/ to
Club: I spoke of spirit & independence, & true
friends." 67 He did not record what Cavendish said
on the subject, if anything, but there can be no
question that there was a friendship and that it was
expressed in the setting of London's coffee houses
and taverns.

"Lillywhite, London Coffee Houses. 160. 201, 699. 792.

H Verner W. Crane, " The Club of Honest Whigs: Friends of
Science and Liberty." William and Man Quarterly 2.? (1966): 210-33,
on 213.

'■-Quotation from the Annual Register, 1783, p 45; in James Sime,
William Herschel and His Wort (New York: Charles Scribner's Sons,
1900), 50.

''"'Entry for 1 Jan. 1782. Blagden Diary, Royal Society.

w On Ktanklin and Aubert: Crane, "Club of Honest Whigs,"
p. 213. On Dalrymple: 15 June 1795, Blagden Diary, Royal Society,
3:62, and elsewhere.

'• s Alexander Aubert to William Herschel, 7 Sept. 1782, Herschel
Manuscripts, Royal Astronomical Society, Wl/13, A 10.

"■Alexander Aubert to Joseph Banks, 1 July 1789, BL Add Mss
33978, no 251.

"Entry for 25 Aug. 1794, Blagden Diary, Royal Society, 3:13.

Copyrighted maBr

©ukes, Duchesses, and Properties

Figurk 1. William Cavendish, Second Duke of
Devonshire. By Charles Jervas. Devonshire Collection,
Chatsworth. Reproduced by permission of the Chatsworth
Settlement Trustees and the Courtauld Institute of Art.

1 9fK

Figurk 2. Rachel Russell, Duchess of Devonshire. Wife of
the Second Duke. By M. Dahl. Devonshire Collection,
Chatsworth. Reproduced by permission of the Chatsworth
Settlement Trustees and the Courtauld Institute of Art.

Figure 5. Kents. Conversation Piece at Wrest Park. By Silsoe, around 1135. Left to right:
Mary de Grey, William Bentinck, Barbara Godolphin, Lord Berkeley, Charles Bentinck, Earl of
Clanbrassil, Countess of Portland, Duke of Kent, Lemima Campbell (later Marchioness de Grey),
Sophia de Grey, Duchess of Kent, Elizabeth Bentinck, Countess of Clanbrassil, Viscountess
Middleton. Reproduced by permission of the Bedfordshire Record Office.

FlGI IRE 6. Chatsworth House. The rountry house in Derbyshire belonging to the
(Jukes of Devonshire. Photograph by the authors.

FIGURE 8. Devonshire House. Picadilly. Demolished. Among aristocratic
mansions in London, this townhouse of the dukes of Devonshire was uncommon
for being detached instead of terraced. Reproduced by permission of National
Monuments Record: RCHMF. © Crown Copyright.

Figure 9. Wrest Park. The duke of Kent's garden at his country house in Bedfordshire. Photograph
fry the authors.

Figure 1 0. No. 4 St. James Square. The duke of Kent's
house in London. Reproduced by permission of the Greater
London Record Office.

The Scientific Branch of the Family

FIGURE 11. Lord Charles, Cavendish. By Enoch Seenuin
(r. 1694-1145). Devonshire Collection, Chatsworth.
Reproduced try permission of the Chatsworth Settlement
Trustees and fry the Courtauld Institute of Art.

FIGURE 12. Lady Anne de Grey. Wife of Lord Charles
Cavendish. By J. Davison. Reproduced try permission of the
Bedfordshire Record Office.

Figi'rk 13. The Honourable Henry Cavendish. Graphite and gray wash sketch
by William Alexander. Beneath the sketch, in handwriting, it reads: "Cavendish
Esqr. F.R.S. Trustee of the British Museum. 1812. " 'The figure measures ten
centimeters. Reproduced by permission of the British Museum.

Places and Instruments of Science

Ficirh 14. No. 13 Great Marlborough Street. Demolished. Lord Charles Cavendish's house from
1 738 to the end of his life. Henry Cavendish lived here with his father, and after his father 's death he
leased the house. View of the back premises in Blenheim Street. From a watercolor sketch of 1888 by
Appleton. Reproduced by permission of Westminster City Library.

FIGURE 15. Church Row, Hampstead. Henry Carendish lived in No. 34 Church Row for almost
four years, from 1 782 to 1 185. Hut for the automobiles, this street with its church and terraced
houses looks much as it did then. Photograph Iry the authors.

FIGURE 16. No. 11 Bedford Square. Henry Cavendish
appears on the rate books for this town house from 1 186 to
the end of his life. Photograph by the authors.

Figure 1 7. The Cavendish House, Clapham. Demolished.
Henry Cavendish Is country house from 1 185 to the end of
his life is shown here from the back, in a later, altered
version. Frontispiece to The Scientific Papers of the
Honourable Henry Cavendish, 2 vols., ed. E. Thorpe
(Cambridge, 1921). All rights reserved: Cambridge
University Press. Reprinted with the permission of
Cambridge University Press.

Figure 18. Chemical Balance. Belonging to Henry
Cavendish. Built fry "Harrison, "probably Cavendish's
private instrument -maker H tlliam Harrison, this instru-
ment is the earliest of the great precision balances of the
eighteenth century. Reproduced by courtesy of the Royal
Institution of Great Britain.

FIGURE 20. Portable Barometer. Belonging to Henry
Cavendish. The ingenious case opens into a tripod.
Alongside the (now broken) barometer are two scales, one
English and one French. There is a thermometer at the
bottom with a correction scale. Cavendish may have used
this instrument on his journeys outside London. Photograph
try the authors. Devonshire Collection, Chatsworth.
Reproduced by permission of the Chatsworth Settlement
Trustees.

FIGURE 19. Battery of Teyden Jars. The box is labeled
"JCM" /James Clerk Maxwell], "Electrical Apparatus
belonging to Henry Cavendish. " Photograph by the authors.
Devonshire Collection, Chatsworth. Reproduced by
permission of the Chatsworth Settlement Trustees.

■

FIGURE 2 1 . Mathematical Instruments. Belonging to Henry Cavendish. The instrument cases in this
and the next illustration are drawers that fit into a cabinet. There are many scales and rulers, a
brass globe map projection, an ivory triangle, and so on, bearing the names of well-known instru-
ment-makers: Jesse Ramsden, Jonathan Sisson, and Fraser, presumably, William Fraser. Photo-
graph by the authors. Devonshire Collection, Chatsworth. Reproduced by permission of the
Chatsworth Settlement Trustees.

Figure 22. Mathematical Instruments. The second drawer contains more brass and wood scales
and rulers. The regular solids are made of hardwood. Cavendish i scientific papers contain many
drawings made with these instruments, including drawings from which the plates accompanying hi
publications were made. Photograph by the authors. Devonshire Collection, Chatsworth.
Reproduced by permission of the Chatsworth Settlement Trustees.

Places of Public Service

FlGl RE 23. House of Commons, 1141-42. From an engraving by Benjamin Cole, after John Pine,
1149. Lord Charles Cavendish represented several successive constituencies in the Commons between
1125 and 1141. Frontispiece, Romney Sedqwick, The History of Parliament: The House of
Commons 1715-1 754, vol. 1 (New York: Oxford University Press, 1910).

Figure 24. Westminster Bridge. Westminster from the North Fast. By Samuel Scott.
Westminster Bridge is shown in an early stage of construction. Lord Charles Cavendish was an
active bridge commissioner from 1136 to 1149, the eve of its opening. Reproduced try permission of
the Governor and Company of the Bank of England.

Figure 25. Westminster Bridge. Westminster Bridge, London, with the Lord Mayor's
Procession on the Thames, 1141. By Canaletto. Westminster Bridge is nearly finished; final
construction can be seen at the far right. Reproduced by permission of the Yale Center for British
Art, Paul Mellon Collection.

Figure 26. Royal Society. The Meeting Room of the Royal Society at
Somerset House 1780-1857. Painting by Frederick William Fairholt and
engraving try H. Melville. Henry Cavendish came regularly to meetings in this
room for the last thirty years of his life. Reproduced by permission of the Royal
Society of London.

FIGURE 27. Foundling Hospital. Demolished. Lord Charles Cavendish was a
governor of this institution from the year of its charter, 1 139. From a contem-
porary print. Reproduced by permission of the Greater London Record Office.

■

Figl'RK 28. British Museum. Entrance to the Old British Museum, Montague House.
Lord Charles Cavendish became a trustee of the Museum at its first election, 1153. Henry
Cavendith was elected a trustee in 1773. Watercolor by George Scharf the elder, 1845. Visitors are
seen entering from the left; through one of the two arched gateways on the right can be seen visitors
on the staircase and stuffed animals on the landing. The statue is of Sir Joseph Banks, former
president of the Royal Society. Reproduced by permission of the British Museum.

FIGURE 29. British Museum. Staircase of the Old British Museum,
Montague House. Watercolor by George Scharf the elder, 1845. Visitors are
shown on the stairs and on the landing looking at stuffed animals. The giraffes
seem to be outgrowing Montague House, which was in a sense the truth, for by the
time this painting was made, most of the contents of the overcrowded and
dilapidated Montague House had been removed to the new home of the Museum.
Reproduced by permission of the British Museum.

FIGURE 30. Royal Institution. Distinguished Men of Science Living in Great Britain in
1 807-8. Engraving by William Walker around 1862, taken from a drawing by Sir John Gilbert.
The setting of this print is the library of the Royal Institution, but the group portrait is artificial.
Henry Cavendish sits apart with eyes downcast, perhaps the artist's interpretation. Cavendish 's
profile and dress are drawn from William Alexander's sketch. Cavendish 's hat has been removed,
and he is seated and faced in the other direction. Henry Cavendish was a manager of the Royal
Institution from 1800. Reproduced by permission of the National Portrait Gallery.

PART 4

c hfcmy Cavendish

Copyrighted material

CHAPTER 1

Propped in the corner of his carriage, Cavendish had
himself conveyed through the streets of London to
his many regular destinations, his clubs, for example,
where by all accounts he cut a somewhat awkward
figure. But he was not awkward at home, where
everything was made to fit. Furnished in the taste
of the scientific revolution, with instruments and
laboratory, his home was the place of his most
intense life. We give over this chapter to Cavendish
at home.

Landlord

For over fifty years, Lord Charles Cavendish
was responsible for farms and tithes primarily in
Nottinghamshire but also in Derbyshire, which
were his for life as a part of his marriage settlement.
Living in London, he administered his estate by
correspondence, delivered by the Nottingham
coach, with his steward, who lived in the
neighborhood. His steward was hired to keep an
eye on the state of his properties, recommend to
him repairs, improvements, and the proper rent to
charge, inform him about the reliability of existing
and prospective tenants and what to do when they
caused problems, which included eviction, treat
with other landlords and surveyors to settle
disputes over enclosures, spend his money to
influence voting in local elections, and, most
important, collect his rents. He was a pleader,
negotiator, spy, and enforcer, who was always
caught in the middle between his distant employer
and the tenants he met face to face. His job was
not easy. This indispensable intermediary for Lord
Charles Cavendish was a man named Cotes, who
had come with a recommender whom Cavendish
could not ignore, the "archbishop." Not further
specified, he might have been the archbishop of
Canterbury, a conscientious trustee of the British
Museum, whom Cavendish saw regularly, but we
suspect he was the archbishop of York, who received
money from Cavendish for paying pensions due

from the rectors' in the parish of Arnold. Cotes was
healthy at the time, but he soon began to decline
irreversibly. Cavendish "perceived the decay of his
understanding for some years" without, however,
taking any steps. "Out of tenderness," and perhaps
also with due respect to the archbishop, Cavendish
"could not dismiss him abruptly." He wanted Cotes
to resign instead, which with the "assistance" of a
confederate of Cavendish Cotes did in 1764. In his
place, Cavendish hired Thomas Revill, a choice he
almost immediately regretted but which he
nonetheless lived with for almost twenty years.'
Revill abused his predecessor, Cotes, and evidently
abused Cavendish's tenants, and Cavendish came
to regard him as a "peevish old man," who created
more problems than he solved. Two words appear
with striking frequency in Cavendish's half of their
argumentative correspondence, "just" and "reason-
able," positive words he never applied to his steward
but to actions his steward did not take and should
have taken. 2

Lord Charles Cavendish introduced his
eldest son to business as he had to science, turning
over the management of his estate to Henry in the
summer of 1782. Lord Charles did not yet formally
make it over, and he continued to participate in its
management, 3 but he allowed Henry to receive the
income, which consisted of rents, tithes, and land
taxes (the tithes were usually rented out), which
amounted to a yearly net income of around £1,600.
At age fifty-one, Henry Cavendish began his life of
well-to-do independence as administrator of ancestral
landed property. His life as an absentee landlord
gives us insight into the man.

'Lord Charles Cavendish to Thomas Revill. 5 Sep. and 13 Dec.
1764. Devon. Coll., L/31/20.

2 Lord Charles Cavendish to Thomas Revill, 31 Jan. 1765, V)
Sep. and 3 Dec. 1776, 12 Apr. 1777, 18 Mar. 1778, Devon. Coll.,
L/31/20 and 34/5.

3 Henry Cavendish to W. Gould, draft, 30 Dec. 1782. Devon.
Coll., L/34/7.

Cavendish

To master the business, like his father
before him, Henry Cavendish had first to settle on
a steward. Thomas Revill, the bad steward, was
still steward, and with his fathers support, I lenry
Cav endish w as determined to replaee him.

(^satisfactorily as he had worked out,
Revill had an extenuating circumstance. At the
beginning of his employment, he had explained to
Lord Charles Cavendish that because of a problem
with his throat, he could scarcely speak and was
reduced to communicating by writing, though he-
was helped in his work by a nephew. 4 Although
Revill's attitude, a mix of sen ility and arrogance,
was exasperating, it seems clear that his near
inability to speak was part of his problem, explaining
the roundabout way he went at his work. His new
master, I lenry Cav endish, w ho himself had such
difficulty speaking that a defect was suspected,
evidently felt no bond of sympathy. He neither
made nor accepted excuses for Rev ill's lapses.

The duke of Devonshire was well served
by his agent, J. W. Heaton, to whom Henry turned
for advice. I leaton recommended William Gould
for his steward, citing his "integrity and judgment
on country business." Through Heaton, Gould let
Cavendish know that he would accept the job. 5
I lav ing lined up Gould, Cavendish turned to the
unpleasant task of firing his father's steward of so
many years. I le told Revill, who had already
written that he wanted to collect the next rents, to
do nothing because he intended to replace him.
Revill protested. In reply. Cavendish said that he
would not have answered him at all but for Revill's
concern that his reputation would suffer. There was
no cause for such concern. Cav endish said, since it
is "so natural" for someone taking over an estate to
entrust it to a steward w hose judgment "he can rely
on." If, however, any doubts about his reputation
were to arise on this account. Cavendish would set
matters right. ( lavendish had meant to end the letter
here but changed his mind, adding that although he-
had no doubt of Rev ill's "fidelity & good intentions,"
he had good reasons for deploring his actions:

the infirmity of your temper which has made you
cither quarrel or behave with petulance to so
many of those you have had business with & the
little information my father could ever get from
you concerning the matters under your charge-
render you very unfit a person to take care of an
estate without which cause I should never have-
thought of employing another stew ard.

To his new steward. Cav endish mentioned Rev ill's
"angry letter," copying out part of his reply to Rev ill,
only in place of "infirmity" of temper substituting
his father's expression, "the peevishness of his
temper." I lis judgment about Revill was confirmed
by Rev ill's behav ior after his tiring: for a full year,
Revill wrote repeatedly to Cavendish to complain of
it. Cavendish neither answered Revill's letters nor
entered them in the index of his correspondence.
Rev ill had no understanding of this new landlord.
The standard by which Cavendish judged Revill
unfit he held up to his replacement: Gould was to
give Cavendish's tenants no cause to complain, and
he was readily to give Cavendish any information
he desired. The first item of business was for
Gould to make a complete examination "into the
condition of the whole estate."''

In Nottinghamshire and Derbyshire, the
Cav endishes had long counted among the big land-
lords who bought out the landed gentry and took over
their manors. 7 Lord Charles and Henry Cavendish's
properties were next door to the duke of I )evonshire's,
from w hich they had been separated off. 8 The duke
of Dev onshire's main country house was in the area,
at Chatsworth, in Derbyshire. Nearby, in Notting-
hamshire, was Hardwiek I lall, where the family
estate records were kept, and where Henry Cavendish
directed his steward to examine documents con-
cerning his properties.'' In matters concerning their lands,
the Cavendishes kept in touch, as a family. When one
of Henry Cavendish's properties became available,
for example, a prospective tenant approached him
through his first cousin Lord John Cavendish. 10 Or

'Thomas Revill to Lord Charles Cavendish, 16 Dec. 1764.

5 W. Gould to J. W. Heaton. 10 June 1782; this letter Heaton
forwarded to Cavendish, adding his recommendation of Gould. I lenry
Cavendish to W. Gould, draft. 8 and 9 Aug. 1782. Devon. Coll., L/34/7.

' Henry Cav endish to Thomas Revill drafts. Hi and 28 Aug. and
5 Sep. I78_': Henry Cavendish to \Y. Gould, draft, 6 Sep. 1782.
Devon. Coll.. L/34/7.

'This practice was complained of in 1625, the earl of
Devonshire being one of the K l| ilt> absentee landlords. J. I).
( chambers, Nottinghamshire in the Eighteenth Century: A Slutly of Life eiuel
Labour under the Squireanhy. 2d ed. (London: f rank Cass. 1966), 7.

"For example. Cavendish received rent from the tithes of
Marston in Derbyshire, the greater part of which parish was owned
by the duke of Devonshire. W. Gould to Henry Cavendish. 28 Sep.
1782, Devon. Coll.. L/34/7.

'Henry Cavendish to W. Gould, draft. 2 Dec. 1787. Devon,
(oil.. L/34/7.

i"VY. Gould to Henry Cavendish. 20 Auk. 17«S; Lord Arundall
Gallway to Henry Cavendish. 21 Auk. 1785; Milnes to Lord John
Cavendish. 24 Aug. 1785; Lord John Cavendish to Henry Cavendish.
25 Any. /1 785/: Henry Cavendish to Lord John Cavendish, draft, n.d.
/reply to letter of 25 Auk. 1785/. Devon. Coll.. L/54/7.

Copy rig hied m aerial

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223

when legislation pended that would affect his
estate, Cavendish was assisted in parliament by
his principal heir, Lord George Cavendish."
Legally, physically, politically, and otherwise,
Henry Cavendish's properties were in the country
of the Cavendishes. Property held them together
as much as they held it together.

From the widely dispersed parts of his
estate, in his first year as manager, in 1782,
Cavendish received twenty-three separate rents of
greatly varying amounts from as many persons,
fifteen in Nottinghamshire and eight in
Derbyshire. Taken altogether, Cavendish's proper-
ties were representative of productive lands in
Nottinghamshire and Derbyshire. On them,
depending on the kinds of soil, a range of crops
were grown, wheat, oats, barley, hay, beans, and
peas, and sheep and cattle were kept as well. The
tilled land was rich in places and marginal in
others; in addition, there was meadow, pasture,
forest, and waste. Like his father, Henry
Cavendish preferred to rent "to Farmers than to
Gentlemen," 1 - and indeed most of his tenants
worked the land themselves. In intelligence,
energy, and responsibility, his tenants varied, and
on occasion Henry Cavendish, like his father, had
to concern himself with their affairs and character.
Having learned that a tenant was in bad financial
straits and in danger of failing, Cavendish in-
structed Gould to inquire if the problem was the
tenant's fault, if he was overextended, extravagant,
incompetent, or whatever and to tell Cavendish
"what you think of him." 13 The disagreeableness
arising from business of this kind Cavendish was
usually spared by his go-between, his steward,
although from time to time he received letters from
tenants directly or even received them in person at
his house. "I did not say much to him," Cavendish
said of one of these uninvited personal encounters,
which he clearly wished to avoid.' 4 Fences, barns,
stables, cowsheds, and houses all had to be
maintained, but this routine business took up little
of Cavendish's time.

This is not to say that Cavendish's estate
did not cause him trouble and worry. It did,
unavoidably; this was the late eighteenth century,
and the enclosure movement in Britain was in full
swing. To show how Cavendish's estate, and
Cavendish with it, were caught up in the complex
problems attending enclosure, we will take as an

example one of his properties in Nottinghamshire.
The problems with it went back to the time when
Lord Charles Cavendish was in charge.

Under the old pattern of farming, tilled land
was parceled into strips with mixed ownership;
meadows, too, were parceled, and pastures were
subject to common rights. To meet changing
economic needs, this pattern was replaced by one
in which strips were consolidated and common
control and use of land were reduced; the device
was enclosure. 1S The practical intent of enclosure,
as Lord Charles Cavendish put it with his usual
clarity, was to "lay each person's allotment together
as much as can be."' 6 Before the eighteenth
century, most of the land suited for pasture in
Nottinghamshire had already been enclosed, but it
was only in the eighteenth century that most of the
land used for grain was enclosed too, and a third of
it was still unenclosed at the end of the century.
Because substantial economic gains could be
anticipated from enclosure, the big landlords and
farmers were for it. If the landowners could not
agree, as occurred in Nottinghamshire where small
freeholders opposed enclosure, an act of parliament
might be required to overcome local resistance. All
but one of Cavendish's properties were in parishes
enclosed by acts of parliament, most of them passed
in the decades of the 1770s through the 1790s, when
the greatest acreage was enclosed by this means
in Nottinghamshire. Lord Charles and Henry
Cavendish were not dominant landholders in favor
of enclosure, and they could not avoid conflict. 17

Fnclosure by parliamentary act followed a
regular procedure. With the support of three-
quarters or four fifths of the landholders, or of one
sufficiently big landholder, a petition for permission
to bring the bill was presented. If the petition was
accepted, an interested member of parliament
would draw up the bill, which was almost certain to
pass without determined opposition. Commissioners

"George Bramwcll to Thomas Dunn. n il., enclosed in a letter
from Thomas Dunn to Henry Cavendish, 14 Dec. 1790, Devon.
Coll.. L/34/10.

'-Cavendish to Lord John Cavendish, draft, n.d. /reply to letter
of 25 Auk. 1785/.

"Cavendish to Gould, draft, 6 Sep. 17K2.

"Henry Cavendish to W. Gould, draft. 7 Mar. 1791. Devon.
Coll., L/34/12.

"Chambers, Snttiiigh«mshin\ 141.

"'Lord Charles Cavendish to Thomas Revill, draft. N/9/ Dec.
1776, Devon. Coll., L/34/5.

"Chambers, Nollin R hamshire, 148, 16.S, 171-73, 202.

224

Cavendish

were then appointed from among the big farmers
and loeal landlords and one or two outside experts.
Their job was to carry out a survey, place the
owners' allotments in enclosed fields, see to it that
the fences, drains, and roads specified in the act
were built, and look into damage claims. Enclosure
was a highly costly improvement: landowners were
out the cost of passing the act, fees for lawyers,
surveyors, and commissioners, and the very
considerable capital expenses of building fences,
drains, roads, and various farm structures. 18

While Lord Charles Cavendish was still
administering the estate, in 1776, the proprietors at
the parish of Arnold in Nottinghamshire considered
petitioning parliament to enclose their land.
Cavendish did not want the petition but since he
could not stop it either, with the help of his
steward he decided what to insist on so that he
would come out unharmed. He was entitled to tithes
from the use of the land at Arnold; from his tithe
tenant, he received rent twice yearly, the total of
which, a little over £100, made Arnold intermediate
in value among his properties. In the event of
enclosure, Cavendish would be expected to forfeit
his tithes in exchange for an allotment of land. Just
how much and what kind of land were the question.

Roughly speaking, the parish of Arnold
contained 1,600 acres of land already enclosed, 400
of open fields, and 30 of glebe, or clerical, land. In
addition, there were about 2,000 acres of common
land, called the "forest," 20 of which, called a
"break," were enclosed in lieu of tithes by
agreement between the tithe tenant and the
parish. The farmers' use of the break for tillage and
the common for keeping sheep was seen as
compensation for the tithes they had to pay for
their open fields and enclosures. 1 '' The quantity of
land at Arnold and the amounts given over to
different uses were imprecisely known, since there
had been no survey. Proceeding from incomplete
information, Revill made proposals to the pro-
prietors about what share of the common fields and
the forest Lord Charles Cavendish should receive
in return for giving up his tithes.

Revill's proposals were ill received by the
proprietors of Arnold, whose spokesman called
repeatedly on Lord Charles Cavendish, bringing
their objections to him in person. Cavendish
wanted them to deal with Revill instead, but they
objected to Revill even more than to his proposals.

Cavendish was told that "there was such animosity
between /Revill/ & the people of Arnold" that the
proprietors believed any agreement with him was
impossible.- 0 Revill was at fault, Cavendish
concluded, by asking for more than was "just," and
by regarding his proposals as absolute demands, a
"peremptory" manner certain to create enemies.
Instead of high-handed practice, reason and
negotiation should be used, Cavendish urged;
Revill should talk with the proprietors. 21 The matter
of the Arnold enclosure languished, but several
years later, in 1782, it came up again, this time in
the form of a petition for a bill. Having just taken
charge of his father's farms, Henry Cavendish faced
a local history of bad feeling."

The recent enclosures had been "attended
with great detriment and injury to the estate," the
new steward Could told Henry Cavendish, by
which he meant not the unavoidable "great sums
that have been expended on those inclosures and
the buildings upon them" but the avoidable,
absolute loss in the value of the estate. 23 That was
what Cavendish was determined to avoid at Arnold
if enclosure should come to pass. He received
hereditary wealth in the form of income off the
land, and in return he was responsible for
maintaining the income for the term of his life. It
was his duty, really a point of honor, to secure the
value of his estate, the measure of which was rent.
To this end Cavendish entered into a long dispute
with the proprietors at Arnold about the amount of
land he was entitled to receive in lieu of tithes. In
principle, it was land equivalent in rental value to
the tithes he would have received from the
improved land after enclosure, but the comparison

'»W. Could to Henry Cavendish, 25 Mar. 1784. Devon. Coll.,
L/34/7. Chambers. Nottingtamhirr, 178, 199-200.

'"W. Gould to Henry Cavendish, 7 and .28 Sep. 1782, 25 Mar.
and 24 Nov. 1784. Devon. Coll., L/34/7.

-"Lord Charles Cavendish to Thomas Revill. draft, 3 Dee. 1776,
Devon. Coll., L/34/5.

-'Lord Charles Cavendish to Thomas Revill, drafts, 19 Sep. and
12 Dec. 1776, Devon. Coll., L/34/5.

"The animosity was clearly generated by Revill's manner. His
proposals were not unreasonable, even if Lord Charles Cavendish
believed them to be. Henry Cavendish's steward asked for the same
share of the forest as Rev ill had. one seventh, which Lord Charles
Cavendish thought was too much, and he asked for a greater share of
the fields, one fifth, than Cavendish thought was right, one seventh.
Lord Charles Cav endish to Thomas Revill, 8/9/ Dee. 1776. VV. Gould to
Henry Cavendish. 31 Dec. 1784, Devon. Coll.. L/34/7. Gould forwarded
the petition from Arnold in a letter to ( lavendish, 28 Sep. 1 782.

"Gould to Cav endish. 28 Sep. 1782.

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of values was not straightforward. Depending on
how it was figured, the farmers benefited more or
Cavendish more.

After a meeting of the proprietors at Arnold
on parliamentary enclosure in 1 784, their spokesman,
William Sherbrooke, wrote to Cavendish to convey
their offer of a specified allotment of land to
compensate him for the loss of his tithes. 24 Gould
calculated the rent Cavendish would receive on
this offer, using current rents and deducting the
interest he would pay for fences and buildings and
the vicarial tithes he would go on paying, as we
discuss below. It came to £169 per year, far below
the £250 Gould estimated Cavendish's tithes
would bring. Cavendish should accept an allotment
of yearly value no less than £360, to be laid out by
the commissioners. That value recognized the
expenses Cavendish would be put to; it was fair,
Gould said, but he felt certain the proprietors
would not like it. 2S But neither did Cavendish, who
explained to his steward that if a value, 360 pounds
or whatever, were proposed, he would come out a
"loser," because the commissioners routinely
overvalued land. He wanted the allotment decided
Sherbrooke 's way (but not at his value), which was
for the commissioners to allot him a certain
"proportion" of the land. That, Cavendish believed,
was a surer measure of the value of the land than
money. 2 '' Gould, of course, accepted his master's
wish, and he advised him accordingly on the
proportion of land to ask for. Gould wanted to
select the location of the allotment on the forest,
but Cavendish thought he was being overly zealous,
making unnecessary trouble for the commissioners,
who might then be "less disposed to do me justice."
Otherwise, Cavendish accepted the proportions
Gould had calculated for him. Cavendish did not
want enclosure, but he was resigned to it as long as
he received his just due. 27

The Arnold proprietors rejected Cavendish's
counter proposals. The land Cavendish would
receive, Sherbrooke said, would rent for £500, and
he knew a man who would pay it. Sherbrooke
complained not just about the proposals but about
Cavendish's steward as well. Cavendish was told of
Gould's refusal to answer letters, to attend the parish
meeting, or even to receive a delegation of "very
respectable men," thereby exhibiting "all the
insolence of delegated authority." 28 Gould, that is,
was behaving just like Revill. Cavendish did not

225

mention to Gould the proprietors' complaint, which
in any event could hardly have been news to him,
nor did he advise him on his behavior relative to
the proprietors. Cavendish, it would seem, had
come to accept confrontation as inevitable, and he
paid his steward to defend his interests and bear
the abuse. He wanted Gould to get more exact
information on acreage, rents, and tithes at Arnold,
for only then could they "prove" that their proposals
were not "unreasonable." Justice in this issue was a
simple matter of arithmetic even though the
quantities involved could be no firmer than
estimates: Cavendish told Gould that justice all
around would be served only if his "estate should
be improved in the same proportion as that of the
land owners." His duty to his estate was to insure
that it received this proportion. His letters to his
steward began to look like laboratory notes. 29

The "affair of Arnold," as Cavendish called
it, dragged on for years.' 0 Early in 1789 Gould
informed Cavendish that enclosure was likely, but
a little later he informed Cavendish that it was
unlikely because the vicar, a hard bargainer, wanted
more for his tithes on turnips and lambs than the
proprietors offered him. Then on 11 March 1789,
Gould told Cavendish that the landholders intended
to go to parliament without the vicar, leaving the
old enclosure and the new allotments still subject to
vicarial tithes. Gould had arrived at an agreement
for Cavendish's allotment of land, which excluded it

24 Thc otter was one eighth of the enclosed land, one seventh of
the open fields, and one tenth of the forest subject to a deduction, to
be determined by the commissioners, for the small vicarial tithes.
Sherbrooke acknowledged that the proportions they offered were
not as large as those granted in some other parishes. VV. Sherbrooke
to Henry Cavendish, 10 Nov. 1784, Devon. Coll., L/34/7.

25 W. Gould to Hcnrv Cavendish, 24 Nov. 1784, Devon. Coll.,
L/34/7.

2 <>Henry Cavendish to VV. Gould, drafts, Dec. and 24 Dec. 1784.
Devon. Coll., L/34/7.

"W. Gould to Henry Cavendish, 31 Dec. 1784; Henry
Cavendish to W. Gould, draft, 6 Jan. 1985 and 2 Dec. 1787, Devon.
Coll., L/34/7.

28 Henry Cavendish to VV. Sherbrooke. draft, 6 Jan. 1785; VV.
Sherbrooke to Henry Cavendish, 3 and 18 Feb. 1785. Cavendish also
received an anonymous letter from a landholder in Arnold
complaining of Gould, Mar. 1785, Devon. Coll., L/34/7.

^Henry Cavendish to W. Gould, drafts, 23 Feb. 1785 and n.d.
/after 28 Feb./ 1785; Henry Cavendish to VV. Sherbrooke, 16 Feb.
1785, draft, Devon. Coll., L/34/7. F'rom Gould's earlier rough
estimates, Cavendish calculated that by the terms he requested, he-
would get £266 annually, which was slightly more than the £233 he
calculated for his tithes and rent of breack should an enclosure not
take place. He wanted better information to refine this calculation.
Henry Cavendish to W. Gould, draft, 20 Feb. 1785, ibid.

"'Cavendish to Gould, draft, 2 Dec. 1787.

226

Cavendish

from vicarial tithes. Cavendish had then to be
given additional land equal to the tithes he must
pay the vicar. The amount was around £15 a year
for Cavendish. 31

Characteristically, Cavendish pressed Gould
for facts on the vicar's turnip tithes. 5 -' It was quite
complicated to know what "part of the turnips are
tithable," and Cavendish felt acute discomfort if he
lacked sufficient reason in making decisions about
his estate, even if the amount of money involved
was insignificant, as it was in this case. Concerning
the vicar's turnip tithes, Cavendish wrote sternly to
Gould that he wished Gould had "explained the
matter to me clearly." Gould had given Cavendish
his recommendations about the turnip tithes
without at the same time giving him his "reasons."
Henceforth Gould was always to give Cavendish
his "reasons." 33

In its own good time, the Arnold affair came
to a close. On 20 March 1789, Gould sent
Cavendish a draft of the Arnold enclosure bill,
which was soon law. 34 News from Arnold would be
bad before it was good again: in the following
summer, Gould told Cavendish that he had
collected the rents from all but two of Cavendish's
tenants, but he was not remitting them. The entire
money was expended in the Arnold enclosure,
going for fences, to the stone getters, and to the
masons who were building the barn and stables.
None of this was surprising. 55

At Arnold and elsewhere, as an administrator
of farm property in a time of enclosure. Cavendish
was a party to the politics of local proprietors, in
itself an activity that came with the family. We give
one more example of an enclosure on his properties
to illustrate how it could also entangle him in the
politics of parliament. As at Arnold, at Doveridge in
Derbyshire, Cavendish owned tithes, which he
rented to a man whose country seat neighbored on
Doveridge, the colorful Irish-born parliamentarian
Sir I lenry Cav endish. The same age as our Henry
Cavendish, Sir Henry was distantly related by
blood and by wealth. 5 '' ("If you were poor, & I rich,
instead of the contrary," Sir Henry Cavendish
wrote to his landlord, the Right Honorable Henry
Cavendish, proposing an exchange of property. 57 )
Like his namesake, though in his case through
politics rather than through science, Sir Henry'
Cav endish was a man of quantity: from Dov eridge,
writing to Matthew Bolton, who ran an alternative

mint to the Tower of London at his Soho works in
Birmingham, Sir Henry said that he was going to
propose in parliament an "Irish Mint," and he
asked Bolton to recommend a man "acquainted
with the Mathematicks, & arithmctick" to assist him
in this project as an amanuensis. 58 At Doveridge, as
at Arnold, Cavendish was confronted by an
enclosure bill, which in its original form entailed a
loss of tithes for him, rational grounds for his
opposition to it. 5 '' This bill stumbled over the same
practical difficulty as the bill at Arnold, that of
getting consent from owners to allocate land in lieu
of tithes. The final bill, which Cavendish did not
oppose, took no notice of the tithes, and the two
I Ienrys entered into a separate agreement on
setting the value of the tithes upon enclosure.

»W. Gould to Henry Cavendish, 9 and 21 Feb., 1 1 and 19 Mar.
1789. Devon. Coll., L/34/12.

'-'Henrv Cavendish to W. Gould, draft, n.d./rcply to letter of 21
Feb. 1789/. Devon. Coll., L/34/12.

"Cavendish to Could, draft, n.d. /reply to letter of 21 Feb.
1789/; W. Gould to Henry Cavendish, 19 Mar. 1789.

M W. Could to Henry Cavendish. 30 Mar. 1789, Devon. Coll.,
L/34/12. Following the preliminary agreements, in which Cavendish
was involved, came the elaborate parliamentary proeedure leading to
the act. The petition was presented; a bill was ordered, presented,
and read; a committee was appointed and reported; the king's
consent was signified; the bill was passed by the Commons; it was
then passed by the Lords with amendments; the amendments were
agreed to; and, finally, the royal assent was granted. Altogether it
took over four months, from March 2 to July 13, 1789.

A Petition of William Coape Sherbrooke. John Need. Robert
Fauley, Edward Jones, anil others. Cords of the Manor of Arnold,
in the County of Nottingham, and likewise, with others, arc
Ow ners and Proprietors of Lands in the Open Common Fields
and Meadows, and entitled to Right of Common in and upon the
Commons and Waste Lands within the said Manor, was
presented to the House, and read; Setting forth. That the Lands
of the Petitioners in the said Fields and Meadows lie intermixed
and dispersed, and. in their present Situation. . . .
With the exception of one proprietor of fifty acres and another of
twelv e acres, all parties gav e their assent to the bill. The whole of the
property affected was 2.(100 acres. No one came before the committee
to oppose the bill. 2 Mar.. 13 May. and 12 June 1789, Journal of the
House of Commons 44: 1 38, 361 , 4.S4, and 456.

'^W. Gould to Henrv Cavendish, 5 June 1790, Devon. Coll..
L/34/12.

'''Sir Henry Cavendish was descended from an illegitimate son
of a brother of the first duke of Devonshire. Historians of British
politics are indebted to him for the shorthand notes he kept of
debates in parliament. His contemporaries had to listen to hot-
headed speeches by him; beside his name on a government list in
1783 is the observation: "A good shorthand writer but a tiresome
speaker." L. B. Namier and John Brooke. Tie House (if Commons
1754-/790, 3 vols. (London: Her Majesty's Stationary Office. 196-4)
2:201-3.

"Sir Henrv Cavendish to Henry Cavendish. 22 Nov. 1 783.
Devon. Coll., L/34/7.

'"Sir Henry Cavendish to Matthew Boulton. 14 Aug. 178K.
Birmingham I'nivcrsity Library.

w Hcnry Cavendish to W. Gould, draft. 2 and 3 Dee. 1790,
Devon. Coll., L/34/12.

Home

During the course of the bill, Cavendish had
defended his property, proposing a clause to the bill,
considering hiring someone to keep him informed
about it, and drawing on the parliamentary offices
of Lord George Cavendish. 40

We might wonder why Cavendish bothered
about his farms at all. After all he had a busy life in
London with absorbing interests of his own
choosing. His farms in northern England did not
even give him the satisfaction a city man might
feel from time to time by standing on land that was
his and surveying a good harvest brought forth
from it by his industrious tenants. From the
questions Cavendish asked of his steward, we get
the distinct impression that he never saw his farms.
He was burdened with landed property on which
he never lived and which gave him endless trouble
for a relatively small income he did not need after
the first year. His steward sent him enclosure bills
to study, and because he owned so many
properties, these bills demanded his attention all
too often for his taste. With regard to an enclosure
that had been pending for two years, Cavendish
wrote irritably to Gould: "You ought to have
informed me of it at the time instead of delaying it
till lately & then representing it to me as brought
in by surprise & without your knowledge /./ I am
very sorry to find that you could act in this manner
& hope I shall never see another instance of any
thing of the kind." 41 Cavendish suffered endless
irritations like this because they came with his life,
and he probably never questioned their need as he
never relaxed his vigilance over his property to
ensure that it was not injured. He managed his
property as a family duty, which if joyless
nevertheless was for a man like him a source of
satisfaction. No matter how far from his family his
activities in science took him, in his occupation
with landed property he was at one with it.

Less compatible with Cavendish's instincts than
political issues was personal confrontation, but he
could not avoid that either in the farm business.
Throughout the time he was occupied with the
Arnold enclosure, he was also dealing with the
consequences of an earlier, completed enclosure at
the parish of Hilton in Derbyshire. The Hilton
enclosure was a "terrible business," Gould said, and
Cavendish agreed, 42 citing his father's experience
there as evidence that the enclosure commissioners

227

overvalued land. Upon consulting a commissioner
at Hilton about the value of Lord Charles's
allotment, Revill had set far too high a rent on it.
Nevertheless it had been taken at that rent, which
might seem an error to Cavendish's advantage, but
it was not. Rather it was the beginning of a long
saga of the imprudent tenant and of Cavendish and
Gould, who had to deal with him. 43

To a man named Rose, Lord Charles
Cavendish had rented the Marston tithes together with
the new farm at Hilton created after its enclosure in
1780. When Henry Cavendish took over the manage-
ment of the estate in 1782, the first problem he
addressed was Hilton. To make Hilton a "compleat
farm," there had been mutual commitments between
Lord Charles Cavendish and Rose, which included
putting up buildings at Cavendish's expense. Henry
Cavendish told Gould to go see what had actually
been done in the meantime. 44 Gould reported that
the buildings were in bad shape, with four feet of
water standing in the cellar, but given the excessive
rent that Rose was paying, Gould doubted that he
could keep up Cavendish's property. 45

Soon afterwards, Rose called on Cavendish
to complain about the value that had been placed
on the land, for the rent was way too much.
Cavendish assured Rose that he would make
allowances for him if he took "good care of the
farm." 46 Rose told Gould that Cavendish had
"ordered" him immediately to build a drain in the
cellar. 47 In dismay, Cavendish wrote to Gould:

I never gave him any directions to get the drain
done. ... I am so much displeased with his

*°George Bramwell to Thomas Dunn. n.d.. enclosed in a letter
from Thomas Dunn to Henry Cavendish, 14 Dec. 1790; Edward
Barwell to Henry Cavendish, 3 Dec. 1790; J. CIcmentson to Henry
Cavendish, 13 Dec. 1790; Lord George Cavendish to Henry
Cavendish, 14 Dec. 1790; Henry Cavendish to Lord George
Cavendish, draft, n.d. /reply to letter of 14 Dec. 1790/. Devon Coll
L/34/10.

41 Henry Cavendish to W. Gould, draft, 12 May 1789, Devon.
Coll.. L/34/12. Gould defended himself against Cavendish's "severe
reprimand" and gave his reasons. W. Gould to Hcnrv Cavendish. 20
May 1789, Devon. Coll., L/34/12.

42 W. Gould to Henrv Cavendish, 8 Dec. 1788, Devon. Coll.,
L/34/12.

■"Henry Cavendish to W. Gould, drafts, n.d. /replv to letter of 28
Feb. 1785/, Devon. Coll., L/34/7.

■"Henry Cavendish to W. Gould, draft, 28 and 31 Aug. 1782,
Devon. Coll., L/34/7.

45 Gould to Cavendish, 28 Sep. 1782.

■"Henry Cavendish to W. Gould, draft, 12 Dec. 1782. Devon
Coll., L/34/7.

47 W. Gould to Henrv Cavendish, 11 Jan. 1783, Devon. Coll.,
L/34/7.

228

behaviour that if it can lie done without
inconv enience I should w ish to get rid of him as
there seems great reason to expect both from this
ex from his offering to take the farm at so much
more than its true value that he will make a very
bad tenant. 4 *

When Gould wrote to him next but did not
discuss Rose, Cavendish noted this omission in the
index of his correspondence. When Gould wrote
again but still did not mention Rose, 4 '' Cavendish
wrote to remind him he was waiting:

I have the more reason too to be dissatisfied with
him /Rose/ as I find he is the only one who has not
paid his rent /./ I must desire therefore that you
will let me know what you think of him ck
w hether he will make a good tenant & if he will
not whether I can remove him without
inconvenience/./ I desire also that you will let me
know what you have done about the drain. 5 "

Gould came to see Cavendish in person. Rose's
drain was finished, but there remained much to be
done on the house. Rose had paid the rent
according to his own valuation, and Gould thought
that Rose might just do as a tenant, besides it
might prov e hard to find another. M

Gould was to change his mind about Rose,
who was Cavendish's one tenant who always fell
behind in his rent. The more dealings he had with
Rose, the more he came to regard him as un-
trustworthy. There came a point when Gould
wanted to give notice to Rose and moreover to
"make a distress on his effects," and he gave
Cavendish a list of Rose's cattle and an evaluation.
( lav endish agreed that Rose would never be a good
tenant and the sooner he was gone the better. Rose-
was not the only, or the first, tenant Cavendish had
considered giving notice to; there had been several
dismissals soon after he took charge of the estate
following Gould's adv ice. But from the beginning
Cavendish and Gould had disagreed on how
tenants were to be treated. Because the tenants
had grown fat off Cavendish's tithes, Gould
reasoned, they could hardly complain of being ill
treated if they were required to quit promptly.
Cavendish, however, was "unwilling to turn out
tenants who have not behaved ill on such short
notice" as Gould wanted, and "a V: year though a
sufficient legal notice would hardly afford them
time enough to provide themselves." 1 *-' In the
particular case of Rose, Cav endish again cautioned
Could in the same v ein:

Cavendish

I would wish to do it /turn him out/ in a manner as
little distressing to him as I can & as I suppose
distraining his effects will besides the expense
oblige him to part with them to great loss I should
be glad if you could avoid that though at the
expense of 'A or even more of w hat is due to me. 5 '

Having been so often deceiv ed, Gould brought the
bailiff with him when he went to see Rose, intend-
ing to make a distress after all. But Rose gave him
apologies and Gould backed down, agreeing that
Rose's son should give security for the rent due. 54

After six years of trouble with Rose,
Cavendish still did not know why he was always so
much in arrears, whether it was extravagance or
poor management. Gould thought it was both, but
he did not know much about Rose either. 5 "
Repeatedly, Cavendish resolved that Rose must go,
and as often he resolved to do him as little harm as
possible, charging his steward with restraint. "It is
in vain to think of continuing Rose as tenant any
longer," but Cavendish did "not mean to act hardly
by him," and he regarded it was only "reasonable"
to forgiv e part of the arrears. 5 '' Cavendish disliked
"violent measures" and "harsh methods," 57 so that
although he wanted to recover what arrears from
Rose he could, he told Gould that "if gentle-
methods will not do I wish you to send me word
before you have recourse to others." 58 But when
Rose would not vacate the farm even after
Cavendish had rebated part of his arrears ("though

•"Henry Cavendish to W. Gould, draft. 15 Jan. 1783, Devon.
Coll., L/34/7.

«W. Gould to Henry Cavendish, 11 Jan. 17N3. Devon. Coll..
L/34/7.

50 Henry Cavendish to W. Gould, draft. 11 Ann- 1783, Devon.
Coll., L/34/7.

"'Cavendish's notes of his conversation w ith Gould in London.
1 1 Sep. 17X3. Devon. Coll.. L/34/7.
^Cav endish to Gould, 16 Sep. 1

53 W. Gould to I lenry Cav endish, 23 Jan. 17X5; I lenry ( lavendish
to W. Gould, draft, o l ei). 17X5. Devon. Coll.. L/34/7.

M W. Gould to Henry Cavendish. 13 Mar. 17X5. Devon. Coll..
L/34/7.

w If the problem had turned out to he that Rose had debts.
Cavendish was willing to buy Rose's land adjacent to his own to
enable him to continue. But if Kose was an incompetent farmer, he-
had to be K»t rid of. Henry Cavendish to W. Gould, draft. 1 Dec. 178X;
W. Gould to Henry Cavendish. 8 Dec. I7XX. Devon. Coll.. L/54/12.

"■Henry Cavendish to W. Gould, draft, 21 Jan. 1790, Devon.
Coll.. L/34/12.

"Henry Cavendish to W. Gould, drafts. Mar. 1790 and 7 Mar.
1791, Devon. Coll.. L/34/12.

s«Henry Cavendish to W. Gould, draft. X Feb. 1790. Devon.
Coll., L/34/12.

Copy rig (nod material

Home

229

if he has hurt the farm so much, as you say, he does
not deserve any thing"), Cavendish told Gould to
take measures to distrain Rose if necessary. Even-
tually Rose left the farm, protesting the expenses
he had been out. 59

Whatever the circumstances, Rose provided
ample evidence that he was a poor manager and
adept at making excuses, playing off Gould and
Cavendish, at least twice coming to London to see
Cavendish. Roses name turns up in the correspon-
dence more often than any other, and Cavendish as
always was jealous of his time. Moreover, like
Gould, Cavendish came to see Rose as devious. Be-
cause Cavendish placed high value on straight-
forwardness in dealing with people, and because
Rose fell short in this as well as in his rent
payments, from early on Cavendish wanted to be
rid of him. Yet he put up with Rose's evasions for
ten years while he kept after his steward for more
facts and advice. There may have been practical
considerations, but clearly the main reason
Cavendish took no action for so long was his sense
of justice, which translated into indecision.
Explaining to Gould why he was ready to forego
part of Rose's arrears, Cavendish said that "it
perhaps would hardly have been worth his /Rose's/
while to hav e taken the farm had he known it would
have been taken from him so soon." 60 And that was
eight years after Rose had become his tenant.

Most of Cavendish's tenants gave him little
occasion for direct involvement. By and large, they
took care of his property and paid him on time.
Their demands or derelictions were occasional and
minor, and as these came up, they were handled
routinely by Cavendish's steward with Cavendish's
advice and approval. From the smooth operation of
most of the properties, little is to be learned about
Cavendish. Fortunately, for what they tell us about
Cavendish, there were the troublesome enclosures
and the troublesome tenant Rose.

Cavendish's early correspondence concerning
his farms reveals him to be new to the business.
His father clearly had handled it by himself until
then. Once the farms were his responsibility,
Cavendish approached their management in the
same spirit with which he approached science. He
set out to acquire a total familiarity with the facts,
and he reasoned from them on the basis of general
principles, including principles of justice, to
conclusions about the actions to take.

Hampstead

Lord Charles Cavendish appears on the rate
books for his house on Great Marlborough Street to
1782, the year before his death. He is followed by
Henry Cavendish for two years, to 1784. Henry
leased the house for many years to Joshua Brookes,
who continued its scientific tradition in a bizarre
fashion. Brookes held a "Theatre of Anatomy" in
Cavendish's house in 1786-98, in which he
lectured and exhibited bodies of notorious
criminals, and in the garden behind the house,
where Lord Charles and Henry Cavendish had
measured the earth and the atmosphere with their
delicate instruments, he built a vivarium out of
huge rocks, and there he chained wild animals.'' 1

Hampstead was the location of Cavendish's
first house of his own. It was no doubt the prospect
of financial independence that prompted and made
feasible his move. His first appearance in the
Hampstead rate books was on 3 January 1782,
which was about the time he prepared to take over
the management of his father's estate and to
receive the rents from it. His last appearance in the
rate books was on 19 September, 1785.''-

William Thornton's contemporary guide to
London and the countryside surrounding it, pub-
lished in 1784, describes Hampstead as follows: this
village located about four miles on the north-west
side of London

was once very small, but by the increase of
buildings is now of considerable extent. Many of
the citizens of London have fine houses here,
because the situation is not only delightful, but
the air is esteemed exceeding wholesome. ... At
the north extremity of the village is a heath or
common, which is adorned with many handsome
buildings, and is so elevated, as to command one
of the most extensive prospects of the kingdom.'''

w Henry Cavendish to W. Gould, draft. Sep. 1790. "When Rose
quitted the farm he petitioned for an abatement on account of
extraordinary expenses he had been at. . . ." Henry Cavendish to W.
Gould, draft, 4 Feb. 1 794, Devon. Coll., L/34/12.

'"Hcnrv Cavendish to W. Gould, draft. 21 Jan. 1790, Devon.
Coll., L/34/12.

'■'"Henry Cavendish to Mr. Joshua Brookes. Counterpart Lease of
a Messuage or Tenement with the Apperts No. in Marlborough Street
in the Parish of St James Westminster County Middlesex," 1788,
Devon. Coll., L/38/35. London County Council. Survey of London. Vol.
31: //;/' Parish of St. Jumes Westminster. Part I: Xoilh of Pimittilh. General
editor F. H. W. Shcppard (London: Athlone Press, 1963), 256.

'-'"Hampstead Vestry. Poor Rate," Holborn Public Library,
London.

'•'William Thornton, ed., AVer, Complete, tine/ Universal History,
Description, and Survey of the Cities of I. on/ton unit W estminster. . .

230

Then, as today, Hampstead was fashionable and
expensive, a draw for Londoners who wanted a
vista and an escape from city stench and squalor.

Hampstead had already begun to change
from a rural to an urban village in the late
seventeenth century, when a mineral springs was
opened there. Hampstead acquired a reputation for
healthiness and a good income from its waters,
which were recommended by physicians who
drank it in quantity. Bottled, the waters were sold
in shops in London, while people traveled to
Hampstead for the cure. Hampstead w as a popular
spa early in the eighteenth century, but it could not
compete with more exclusive spas such as Rath
and Kpsom. It remained a resort while its continuing
growth owed to prosperous Londoners, such as
Cav endish, taking up residence there.' 14

befitting a convenient, healthy, and
handsomely situated v illage, Hampstead hosted its
share of prominent people. The actors Barton
Booth, Robert YVilks, and Colley (libber stayed
there during the summers to plan for the next
season. Among writers, Alexander Pope, Mark
Akensidc, Richard Steele, John Gay, and John
Arbuthnot lived or visited there. 1,5 But the popular
association of Hampstead with artists stems from
the time of John Keats and Leigh Hunt in the next
century. Kighteenth-century Hampstead attracted a
more substantial society: physicians, lawyers,
bankers, publishers, booksellers, and West and Last
Indian merchants. Cavendish, the aristocrat, chose to
liv e among people of business and the professions/ 16

There was the occasional Hampstead
resident with interests overlapping Cav endish's. One-
was the great Shakespeare scholar George Steev ens,
who w as also a Fellow and sometime council member
of the Royal Society and a common guest at Joseph
Banks's conversaziones. , 67 Before Cavendish moved to
1 [ampstead, the famous clock-maker John Harrison
lived there.' 1 * Residing only a few doors from
Cavendish was, we suppose, his favorite instrument-
maker Edward Nairne,' 1 '' from whom Cavendish
may have learned of the house he took.

Cavendish's house was number 34, Church
Row. Church Row was the street of choice in
Hampstead, where the important residents and
visitors congregated and persons of "quality" prome-
naded. The street has not much changed since the
eighteenth century-: the houses today are three-storey,
complete with attic and basement, with a uniform

Cavendish

terraced appearance. In the gardens behind the houses,
there was never stabling, which suggests that the resi-
dents did not go daily to London by private carriage. 7 "
The Hampstead house was Cavendish's
second house. For a time after his father died, he
kept the Great Marlborough Street house as his
townhouse, where he was as apt to be found as in his
new house. 71 At least some of his scientific work he
moved to Hampstead. Blagden helped Cavendish
with experiments and instruments connected with
freezing mercury at Hampstead during his first
winter there. 7 - Nairne helped him compare the
clean air of Hampstead with the foul air of the city. 73
Cavendish determined the error of the time given
by the meridian line by comparing the times of
rocket explosions observed at Hampstead with
those at Greenwich and at Loam Pit Hill. 74 The
brick, plainly attractive Hampstead parish church
at the end of Church Row, rebuilt in the 1740s, and
standing as a symbol of the growth and prosperity
of I lampstead, served Cavendish as the prominent,
nearby object for determining the bearings of his

Likewise the 'loa ns. Villages, Pah/res, Seals, anil Country, to the Extent of
Above Twenty Miles Round, rev. ed. ( I -ondon, 1 784). 482.

M Alcx J. Philip. Hampstead. Then and AW. An Historieal
Topography (London: George Routledge, 1912). 45-46. V. M. I..
Thompson, Hampstead: Building a Borough, 1650-1964 (London:
Routledge & Kegan Paul. 1974). 20-22. 24.

^Daniel Lysons, Environs of London; Being an Historical Account
of the loa ns. Villages, and Hamlets, aifhin Twelve Miles of That Capital.
vol 2: County of .Middlesex (London, 1795). 535-56.

"Thompson. Hampstead, 27—30,

'""Biographical Anecdotes of George Steevens. st|. "
Gentlemen's Magazine, Feb. 1800, pp. 178-80. on p. 180.

'•"Thomas J. Barrett, The Annals of Hampstead. 3 \ols. (London:
Adam & Charles Black, 1912) 2:67-68.

'''We arc assuming that it was the Edward Nairne who was one of
three persons in the fate hooks listed at number 21, Church Row.
Cavendish lived in number 34; see below. "Hampstead Vestry. Poor
Rate." A few years before, a paper by Nairne was headed
"I lampstead": "Experiments on Water . . . from the Melted Ice of
Sea-Water . . .." PT 66 (1776): 249-56. Later Cav endish and Nairne
did experiments together at I lampstead: see below.

■"Stabling could be had elsew here in the village, and coach service
into London was very convenient, there being between fourteen and
eighteen return trips a day. Barrett. Annals of Hampstead I: 279-80.
Thompson. Hampstead, 25, 56. "Hampstead Vestry. Poor Rate."

"'Blagden. wanting to see Cavendish, left a message for him at his
"town house," believing him to be at his I lampstead house. Charles
Blagden to Joseph Banks. 24 Dec. 1785. BM(NH), DTC 3:176.

"Entries for 17 Dec. 1782 and 15 Jan. 1785, Blagden Diary.
Royal Society. 1.

"Henry Cavendish, minutes of experiments on air. 15 and 16
Mar. 1782. Cavendish Mss II, 5:189.

7J Cavcndish began these observations by stating the distance-
between his tow nhouse and his country house: "I lampstead is 182 miles
or 10.2 seconds of time west of Marlborough street & Marlborough
street is 51" west of Greenwich & Greenwich is 5. "4 east of Loam pit
hill & therefore Hampstead is 25. "8 west of Loam pit hill."
Cavendish Mss, unclassified.

Home

231

oamDriage

Putteridge

Hampstead

Hackney

Great Marlborough St

Claphaa

I'LATK VII. Map of Henry Cavendish's Homes. The places where Cavendish is known to have lived are shown on this map of London and its
suburbs. To the north, off the map at the top, are Cambridge, fifty-odd miles from London, and Putteridge, about half as far.

new location, no doubt in connection with William
Roy's great trigonometrical survey at just this time.
From his house on Church Row, Cavendish took
measures, using a theodolite and two stations in his
garden, of the distance and bearing of the closest,
the kitchen, window to the church. He sighted on
the church's weathercock, and from the steeple, he
or an associate took angles with a quadrant of conspic-
uous objects in the surroundings. So commanding
was the view from Hampstead's hill that Cavendish
was able to take in much of London and its out-
lying villages with his instrument. He could look
down on the properties of his family, the duke of
Devonshire's palladian house at Chiswick and the
Bentinck chapel, and on a variety of temples, gazebos,
and pagodas, and on the steeples of Walton, Batter-
sea, Hammersmith, Stretham, Acton, Paddington,
Chelsea, and Ealing, and even on the steeple of the
church at Clapham Common, on the far side of
London, where Cavendish would soon own his
next country house. 75

Bedford Square

But for his Cambridge years. Cavendish
lived all of his life in London. His move to
Clapham Common in the summer of 17H5, like his
move to Hampstead a few years earlier, was a move
not away from London but to a convenient suburb.
He always kept a townhouse as well. Sometime
after 1784 he rented out the house on Creat
Marlborough Street 76 and bought a new townhouse
not many blocks away, on Bedford Square.

Cavendish was not a man who changed
addresses easily. Evidence that his moves in mid
life were attended by turmoil can be read into the
fate of his assistant, Charles Cullen, son of the

"Cavendish had help with the observations taken from the
Hampstead church steeple, as the angles were written in another's
hand; dated 23 and 25 July 1783. There arc a great many sheets of
observations of bearings, with dates falling between 1770 and 1792,
among the unclassified papers in the Cavendish Mss.

lh Sutxey of London, vol. 31, Part 2, p. 256.

Cavendish

famous Edinburgh professor of medicine, William
(allien. We have pointed out that Cullen had been
Blagden's teacher, and it is no doubt through this
connection that Cullcn's son came to be employed
by Cavendish. (Cavendish was accustomed to
having assistants in his researches, as he was
accustomed to having servants in his life, and no
doubt sometimes they were one and the same. In
memoranda on his earlier electrical researches, he
referred to an assistant named "Richard.") William
Cullcn's son had "unluckily fallen" into needy
circumstances, financial it sounds like, and Blagden
was helping him. 77 In June 17S4 Blagden wrote to
Cullen that his son was working out well, though
there is a hint in the letter that he was not, which
was probably the reason for the letter. Blagden
mentioned that the young man had been totally
unfamiliar with a certain book and with Caven-
dish's studies. Cullen had told Blagden of his
"utmost respect for the character of Mr. Caven-
dish," but he clearly had had no direct contact with
him. and perhaps to reassure Cullen that his son
was in good hands, Blagden said that Cullcn's
respect for Cav endish was "no more than his due"
and that Cavendish w as a person not only of great
scientific ability but one who in private life was
distinguished for "the strictest integrity, the most
amiable candour cv a truly philosophical simplicity
of manners." 7 * In November we hear that Charles
(Allien was considering resigning because Cavendish
was dissatisfied with his skill and knowledge of
books. I le accepted the criticism, but he also had
an excuse, which he hoped would earn him a
reprieve: "the moving from Marlboro Street to
Bedford Square" had distracted him from his
regular work, which he had put off until "after the
house was a little more settled." 7 ''

Located in the west end of London, Bedford
Square is one of the many squares that were laid out
in the seventeenth and early eighteenth centuries,
imparting a measure of order to the urban sprawl.
These squares w ere the joint venture of the owner
of a large estate and builders, who were granted
long-term leases and low ground rent. Typically, the
houses had to be of a certain kind and v alue; they
were expensiv c, which is why they tended to be the
addresses of aristocrats and gentry/ 11

The duke of Bedford's 1 12-acre Bloomsbury
estate was conv erted into several large gardens and
squares, one of which was Bedford Square, a

rectangular development measuring 520 by 320
feet between houses. The duke granted Henry
Cavendish a ninety-nine-year lease beginning in
1775, eleven years of which had expired, which
meant that in eighty-eight years the land would be
returned to the heirs of the duke. In 1786
Cavendish entered the rate books, which show that
the immediate predecessor in his house, number
11 Bedford Square, was his first cousin, the
parliamentary leader Lord John Cavendish. The
house came with obvious family connections, with
the Cavendishes and, through the duke of Bedford,
with the Russells. Bedford Square, the most
ambitious example of town planning in eighteenth-
century London, is intact today, and on each side of
it, one can still see the original block of nearly
uniform, three-storey, brick houses, built of
specified materials, dimensions, and design. The
middle of each block of houses is distinguished by
a prominent, stuccoed facade, ornamented with
pediments and pilasters, and the entrance doors of
the houses are crowned with varied, rounded
fanlights. 81 In style, Cavendish's house is the same
as that of the blocks of houses, but it does not
physically join them. It is an end-of-row house on
the northeast corner of the square, on Cow er Street,
with its entrance on Montague Place. The house,
since taken over for offices by the nearby University
of London, carries a plaque identifying it as having
once belonged to the chemist Henry Cavendish.

"I have scarce ever met with a more substan-
tial or better built House, and the whole Edifice is
finished with the best materials," an appraiser
wrote of Cavendish's house on Bedford Square.* 2
Cavendish appreciated value. The floors of the two

"-William Cullen to Charles Blagden, 8 May 17X4. Blagden
Letters. Royal Society, (70.

; "CharIes Blandcn to William Cullen. 17 June 17K4. draft.
Blagden Letterbook, Vale.

7 ''Charlcs Cullen to Charles Blagden, 7 Nov.1784 anil "Monday"
/l 7K4/. Blagden Letters, Royal Society. C.62 and C.63. Perhaps it did
work out; there is one more letter from Charles Cullen to Charles
Blagden, n.d., ibid., CM. which says that Cavendish finds that
Macquer's chemical dictionary with Bergman's notes is almost out of
print, and Cullen wonders if he minht bring out a new edition. He-
says he has been asked to do a translation of this kind.

"•George Rude. Hanoverian London, 1714-1808 (Berkeley:
University of California Press. 1471). 11-14. London County
Council, Survey of London, vol. S: The Parish of St. Giks-in-the-Fields,
part 2 (London: 1914), 1 50.

^Survey of London, vol 5, part 2, p. 150. Rude, London. 14.

"-'"Mr. Willock's Valuation of I louse cv Stables in Bedford
Square," a letter from John Willock to John Heaton. 30 Dee. 1813,
Devon. Coll., L/34/10.

Copyrighted material

1 1 nun

233

main storeys of the house were of Norway oak and
the hall and staircase of Portland stone. All three
storeys and the attic for the servants had bowed
windows to the back, which, like the veranda,
overlooked a deep garden. Detached from the
house and located at the bottom of the garden were
a double coach house and stabling for five horses.
These outer buildings had been converted to an-
other use, their entrance on Montague Place walled
up, and new, equivalent coach houses and stabling
built opposite them opening onto Keppel Mews.*-'

Cavendish's Bedford Square house is best
described as a green, live-in scientific facility. The
color scheme of the furnishings was consistent:
green moreen window curtains, green transparent
canvas-lined mahogany blinds, green chair covers,
and fire screens covered with green silk. The
furniture was mahogany.* 4 By far the greatest part
of the house was given over to books and such fix-
tures as book users require. 85 The house may also
have been used to display Cavendish's mineral col-
lection. 8 '' With the exception of the dining and back
parlor rooms, all of the main rooms had book-
shelves. So altered was the house that, according to
an estimate after Cavendish's death, a sum equal to
a quarter of the value of the house would have
been required to restore it to a condition "fit for
the residence of a family." 87

Klsewhere we discuss the nature of
Cavendish's books and the use of the Bedford
Square house as a semi-public library; here we limit
our account to a physical description of the altered
house. The main entrance to the house opens onto
a large hall, to the left of which is the dining parlor,
which was used as intended. To the right of the hall
is a room called the lower library with bookshelves
consisting of 90 sliding shelves mounted on 20
uprights. The uprights, fitted with plinth and
cornice, no doubt extended from floor to ceiling.
Off of this library to the right is an adjoining room
where a copying machine was located, a double-
roller apparatus by Watt & Co., and here there were
bookshelves consisting of 14 uprights and 93 sliding
shelves. From this room, to the left, is an adjoining
room, which had 10 uprights, sliding shelves, and a
cupboard for maps. The floor plan shows curved
stairs opposite the entrance hall leading from the
ground floor to the principal floor, which Cavendish
evidently gave over entirely to library use. It is

here that the main library room was located, with
its 28 uprights, 268 sliding shelves, Wedgwood ink
stands, high and low steps, cushioned chairs, desks
and table, and a table clock. The next floor, the
two-pair floor, also had rooms for books, but they
were not equipped with tables and chairs for
readers. This private floor held what was called the
upper library, which was fitted with 18 uprights and
121 sliding shelves. The room adjoining it had 10
uprights, more than 40 sliding shelves, and a set of
bookshelves with six folding doors. There was also a
small room to the front of the house containing 5
uprights and 15 sliding shelves. Even Cavendish's
bedroom on this floor had a bookcase with a glass
door ami bookshelves with 3 uprights ant! 16 sliding
shelves. 88 This enumeration of uprights and
shelves is intended to convey a correct notion of
what was essential about the Bedford Square
house: it was a house of books, with little room for
anything else. Its owner was a bookish man, who
not only collected books, as rich men then did, but
also read them. The Bedford Square house was a
material expression of Cavendish's single-minded
quest for a scientific understanding of the world.

If it were not the embodiment of a rare
intellectual force, the Bedford Square house might
seem to be nothing but so many yards of occupied
shelving, a place of utmost ////personality. This
impression is reinforced by the use of the house as
a public place, where books were checked out to
qualified users by a salaried librarian. 8 '' Yet in the
selection of books, as we will see, the Bedford

1 1 The Particulars o f a Capital Leasehold House and C Offices Situate at the
North East Corner of Bedford Sr/uarr . . . Sold fry Auction, In Mr. Willorh . . .
The Twenty-ninth of April, 1X14 . . . Wiilock to I leaton, 30 I tec. 1814.

""Inventory of Sundry Fixtures, Household Furniture, Plate,
Linen etc etc. the Property of the Late I lenry ( endish Esquire at
His Late Residence in Hedford Square. Taken the 2nd Day of April
1810," Devon. Coll., L/l 14/74.

w Of Cavendish's Bedford Square house, George Wilson says
that "books and apparatus formed its chief furniture": The Life of the
Honourable Henry Cavendish (London. 18.S1), 16.5. At first Cavendish
kept considerable apparatus in this house, but at the end of his life
there was almost none.

"'That is the likely meaning of "museums." the word appearing
in the appraiser's report. The rooms of Cavendish's house, he wrote,
"have been many years used as Libraries, and Museums, and are at
present in that state. . . ." Wiilock to I leaton. 30 Dec. 181.?.

1,7 After Cavendish's death, the house in its present state was
appraised at £4.000. The cost of making it tit lor human habitation
was estimated at £1,000 to £1.200. W iilock to 1 leaton. M) I )ec. 1813.

"""Inventory of Sundry Fixtures. Household Furniture, Plate.
Linen etc etc."

"Cavendish's last librarian, w ho did not liv e in the Bedford Square
house but on the Strand, received a yearly salary of £13. "Collingwood,
the Librarian, One Years Salary DueXtmas 1811," Devon. Coll.

234

Square library expressed the personality of its owner;
it was not a gentleman's library meant to impress
the outside world but a library to serve its owner.
Limited as w ere the other eontents of the Bedford
Square house, they too revealed Cavendish's per-
sonality. The inventory of the house ineluded a
category "Paintings." Cavendish was not an art
collector like his grandfathers; he hung paintings in
his house not because they were art but because of
their subject. I lis paintings included four three-
quarter portraits of members of the Cavendish
family and one small portrait of an earl of Devonshire.
In addition, in storage he kept ten damaged family
portraits. The paintings in the Bedford Square house,
otherwise devoted to scientific books, expressed
the other side of Cavendish's identity: as well as a
man of science, he w as a Cavendish. 90

Apart from seeing to it that the books were
cared for. Cavendish had few needs at Bedford
Square, and he kept only three servants there, a
porter, a housemaid, and a cook.'" He sometimes
stayed in the city at his Bedford Square house,
which was just around the corner from the British
Museum and convenient to the Royal Society. He
kept appointments at the house, too.

For the last twenty-five years of his life,
Cavendish's scientific establishment consisted of
two houses, one at Bedford Square and one at
Clapham Common (which we will get to). In
certain ways they duplicated one another: in their
valuations, the furnishings of the Bedford Square
house and those of the Clapham Common house
were almost identical.''-' There was a good deal of
plate, linen, and china at both houses, though there
was more at Bedford than at Clapham, which
might be expected of a townhouse. 93 Cavendish
devoted to them the familiar aristocrat's attention to
his houses, though their function was unfamiliar.
His houses were, in their own terms, "great"
houses, only not in the sense of "piles" but of their
arrangements. They were houses of science, which
have to be seen together to be properly appreciated.

To keep order in his life in two houses,
Cavendish drew up a list of keys under various
headings, including under "instruments." He kept
a small but choice selection of instruments at
Bedford Square, made by John Bird, Jeremiah
Sisson, and Edward Nairne, among others. They
were the kinds of instruments to be expected:
microscopes, presumably for the minerals kept at

Cavendish

Bedford Square, and instruments for taking measure-
ments at a fixed location: astronomical telescopes,
quadrants, and clocks, and magnetic dipping
needles. 1 ' 4 Cavendish kept most of his large collec-
tion of instruments at Clapham Common, where
he made most of his observations and experiments.

Just as Cavendish made some observations
at Bedford Square, at Clapham Common he kept a
small library; the division of functions of his two
houses was not absolute, but at the end of his life,
it was nearly so. Bedford Square then had clocks by
John Shelton and Richard Graham and a couple of
thermometers and a barometer, but these were
instruments that might be found in any gentle-
man's house. In the valuations of the two houses,
only at Clapham Common were scientific instru-
ments listed.''' 1 Cavendish's investment in books
was far greater than in instruments. The value of
his books at Bedford Square was truly enormous,
over twice the combined value of the total contents
of both houses and twice the value of the Bedford
Square house itself.'" 1 Scientific books were very
expensive. Cavendish's Bedford Square house
stood for scientific knowledge already attained, as
recorded in books and journals, and his Clapham
Common house stood for knowledge in progress,

'"'"Inventory of Sundry Fixtures." He had one painting that was
not a family portrait, a landscape.

'""Wanes Due to the Servants at Clapham and Bedford Square,"
Devon Coll.

''-The household furniture at the Clapham Common house was
valued at £645.10.6, at the Bedford Square house at £633.13.1.
"Extracts from Valuations of Furniture etc.," Devon. Coll.

'" The value of the plate, linen, and china at Bedford Square was
four times the value of the same at Clapham Common, £699.16.8 vs.
£168.4.0. "Extracts."

' l4 Thc kess are listed undet headings L.l through L.6, which
might stand for "London," and "Clapham No. 1" followed by Nos. Z
through 4. The Clapham No. 1 keys were, he noted, "carried about
me," some or all of which fit Bedford Square locks. The other "N"
keys may have been for Bedford Square or they could have been
duplicates for Clapham Common. There is a key for "Observatory,"
which we know Cavendish had at Clapham Common but which he
probably also had at Bedford Square. In any case, the instruments
under lock and "N" keys are of the same type: microscopes and
astronomical instruments by excellent instrument-makers, such as
Jesse Ramsden, John Dolland, and John Hadley. There were two
instruments that do not fit the abov e description: an air pump and an
electrical machine. "Keys at London," Cavendish Mss. unclassified.

,5 Under the category of philosophical and astronomical
instruments, Clapham Common was listed at £544.19.0 and Bedford
Square at nothing. "Extracts."

'"'Cavendish's books at Bedford Square were valued at £7,000.
Thomas Payne to John Heaton, 6 Sep. 1810. After Cavendish's
death, his Bedford Square house brought £3,530. "29 April etc. 1814
Account Respecting the Sale of a Leasehold House at the North
bast Corner of Bedford Square," Devon. Coll.

Ho nir

235

experiment and observation. Dedicated totally to
scientific pursuits, Cavendish's two houses
complemented one another.

The Library

Practitioners of science in the eighteenth
century rarely could afford to buy or subscribe to
many scientific books and journals. Large scientific
libraries were a luxury of the rich. Like Hans
Sloane, Joseph Banks, and other collectors, Henry
Cavendish, and probably his father before him, 1 ' 7
made his library available upon application. This
private man allowed the library in his house on
Bedford Square to be used as a public institution. 98
He ran a tight ship. There was a catalogue of all the
books and a take-out register and a librarian to
watch over both and, as well, over the books, the
patrons, and, most important, his masters wishes.
When the twenty-one year old Alexander
Humboldt traveled to London in 1790, he applied
for permission to use Cavendish's library, which he
received together with the advice that under no
circumstances was he to talk to Cavendish if he
should see him there.'' 1 ' (Later Cavendish took an
interest in Humboldt's measurements with a
eudiometer, which Cavendish thought were wrong
due to a faulty method; 100 and Humboldt took
satisfaction at succeeding to this haughty aristocrat's
place in the Paris Institute.) The request from
another reader was communicated through Blagden,
who explained the official policy. "Wishing to
promote science by every measure in his power,"
Cavendish made his library accessible "at all
seasons of the year." Blagden made it clear that
what was accessible was the library and not its
owner: Cavendish did not want people even to sit
in his library but to "borrow such books as they
wish & take them home for a limited time." 101 To
further this policy books would even be sent to
borrowers. 102 Even with these rules in effect,
ordinarily it was not Cavendish but his librarian
who met the public. 103 In addition to aiding
persons in their researches, the librarian acted as
the lion at the gate, guarding Cavendish's privacy,
if imperfectly. One who got by him was Pahin de
La Blancherie, who was in London on a visit. La
Blancherie complained to Cavendish about the
treatment he received from his librarian. Having
requested a history of astronomy (shelved on the
ground floor, just to the left of the entrance), he

was told by Cavendish's librarian that Cavendish
had just taken that book to Clapham Common. He
then asked for a biographical dictionary; the
librarian told him that Cavendish had taken it too.
The librarian told him to come back, which he did,
whereupon the librarian told him that Cavendish
still had the books and moreover had great need for
them. La Blancherie had been thwarted at the
British Museum and now at Cavendish's library,
and he thought the British nation owed him damages.
He knew that Cavendish would not authorize this
conduct by his librarian but would condemn it. 104
We are not so sure.

One of the rare stories of Cavendish's
largesse concerns his librarian, who lived in his

'''At least we know that Lord Charles Cavendish lent books to
friends; e.g., he lent Thomas Birch the latest book by the
metaphysician Dobbs, an enquiry into being, A Miscellaneous
Metaphysical Essay. Birch to "Dear Sir." 18 Oct. 1748. draft, British
Museum. Add. Mss. 4324 A. f. 1.

''"There is some question about the location of Cavendish's
library. Wilson says that for his library, "Cavendish set apart a
separate mansion in Dean Street. Soho." For this information, he-
cites Cavendish's early biographers ( luvier anil Biot. But all that Biot
says is that Cavendish located his library two leagues, or five English
miles, from his residence so as not to be disturbed by readers
consulting it, and five miles is roughly the distance from Clapham to
the center of London. Since neither Biot nor Cuvier mentions Dean
Street, Wilson supplied this address from unknown sources. Georges
Cuvier, "Henry Cavendish." in Gnat Chemists, ed. E. Faber (New
York: Interscience Publishers. 1%1 >, 227-38, on 237; J. B. Biot.
"Cavendish (Henri)." liioffufthie Vniverselle, vol. 7 (Paris, 1813),
272-73. on 273; Wilson, Cavendish, 163. We have found no other
record of Cavendish at Dean Street. At the end of his life,
Cavendish's library was in his house on Bedford Square, and we arc-
inclined to think that Wilson's source got the location wrong.

"Humboldt's irrepressible talkativeness may have had
something to do with the advice that in Cavendish's library "he was
on no account to presume so far as to speak to, or even greet, the
proud and aristocratic owner should he happen to meet him." This
anecdote from Bruhn's biography is quoted in James Thome,
Environs of London (London, 1876) 1: 111.

""'Henry Cavendish to Chatles Blagden, 18 Dec. Blagden
Papers, Royal Society.

""Charles Blagden to Thomas Beddoes, 12 Mar. 1788, draft,
Blagden Letters. Royal Society, 7:129.

"'-Blagden told Herschel that Cavendish had the books he-
wanted to borrow and that Herschel could cither look at them in his
library or have the books sent to him at Slough. Charles Blagden to
William Herschel, 19 May 1786. draft, Blagden Letters, Royal
Society, 7:762.

lor Thomas Young said that after Cavendish's librarian died.
Cavendish himself devoted one day a week to checking books in and
out of his library. 'Thomas Young. "Life of Cavendish." originally
published in the supplement to the Encyclopaedia Britannica for
IH18-1824; it was reprinted in Cavendish, AW. I'/ip. 1: 435^17, on
445. Cavendish had a librarian at the time he died, but given the
small salary he was paid, he might not have been expected to check
books in and out among his other duties. "29th May 1812. 'Taxes etc.
for 1 louse in Bedford Square," Devon. Coll.

l04 Pahin de La Blancherie to Henry Cavendish, 23 Feb. 1794,
Cavendish Mss. New Correspondence.

Cavendish

house but who eventually left Cavendish's
employment to live in the country. At his club
Cavendish was told that his former librarian was in
poor health. Cavendish was sorry to hear that. It
was then suggested that Cavendish might help him
out with an annuity. "Well, well, well, a check for
ten thousand pounds, would that dor" 105 Truth or
tall tale, there is reason to think that Cavendish
hail got satisfactory sen ice from this librarian.
Despite Cavendish's reputation for clockwork
routine, he was not particularly good at keeping
order in his affairs and his things, including his
books, which were described as being in a "bad
state of arrangement."""' He needed help. The
librarian made a catalogue of his and his father's big
library and entered it in a great, heavy volume of
blank pages (the entries are in more than one hand,
none Cavendish's), and he physically arranged and
dispensed the items listed in it. He was also
Cavendish's live-in linguist, a German 1 " 7 by the
name of I leidinger, evidently. 1 "* Cavendish did his
part to preserve the system created by his librarian,
signing for every book he borrowed like any
stranger off the street. 1 "' 1

With the exception of about 450 books in
their original paper covers, 11 " Henry Cavendish's
books are now bound in leather and dispersed
among the other books of the great ducal library at
Chatsworth, 111 most of them shelved in the
beautiful, old Long Gallery. Cavendish's books are
identifiable both by his book stamp, a simple HC,
and by his separate catalogue number. The
catalogue of Cavendish's library is incomplete,
since it includes new entries only into the early
17°0s, which is probably when his German left,
and we know that Cavendish continued to buy
books after that time. For this reason we can speak
with greater accuracy of the contents of his
catalogue than of his library. 11 - The catalogue lists
about 9,000 titles, representing some 12,000
volumes."-' Cavendish's library was large but not
immense for the time. Sloane's library was four
times as large, and even Cavendish's sea-going
friend Alexander Dalrymple had a library larger
than his. (Dalrymple was unusual; not a rich man,
he had a great library, which may be why he was
often in debt and borrowed money from
Cavendish. ) ,u Many of Cav endish's colleagues had
substantial libraries though of an order of
magnitude smaller than his. Ncvil Maskelyne's in

1811 contained 757 lots; John Playfair's in 1820,
1421 lots; Charles Hutton's in 1816, 1854 lots.
Notable libraries by professional persons tended to
be libraries of physicians; William Cullen's, for
example, contained 3010 lots." 5 Cavendish's
library was intermediate in size; that it was not
even larger was because it was selectiv e. Although
it was open to a qualified public, its contents were
not selected for the public. The works it contained
were works that interested the Cavendishes. 1 "'
The largest category of his collection is natural
philosophy with nearly two thousand titles.

""Wilson, Cavendish, 174.
""•Ibid.

""Thomas Young, "Life of Cavendish," Encyclopaedia
Britannica, Supplement, 1816-24: in Cavendish, Set. Pap. 1:435—' 17.
on 445.

'""Cavendish did not read German fluently if at all, and he
certainly did not read German script. Blagden, who did read it. was
out of town when a letter from the German chemist Lorenz (;rell
arrived. "I hope you got Mr. Heydinger to read Crell's letter."
Blagden wrote to Cavendish. Letter of 2.? Sep. 17X7. Cavendish Mss
X(b), 14.

""Georges Cuvier, "Henry Cavendish," translated from the
French by I). S. Faber, in E. Faber, ed.. (Unit Chemists (New York:
Interscicncc Publishers. I%] ). 227-.sK. on 2.V7.

""Listed as "Cavendish Tracts Draft Catalogue 1966." These
hooks may have been bound and shelved with the others by now.

'"Five years after Henry Cavendish's death, the sixth duke of
Devonshire brought together the books from his several houses to
make the great Chatsworth library, and Henry Cavendish's books
vsere included, a gift from his heir. Lord George Cavendish.
Historical notice by J. P. Laeaita, July 1X79, on p. xvii of vol. 1 of
Catalogue of the Library at Chatsworth. 4 vols. (London. 1879). Henry
( ;a\ endish's books constitute about one quarter of the ducal library.

" 2 Thc catalogue is not identified as Henry Cavendish's, but an
inspection of books ow ned by Cavendish in the Chatsworth library
confirms that this catalogue lists those books; penciled in the books
are numbers that correspond to the numbers of the catalogue.

" This count is given in R. A. Harvey. " The Private Library of
I lenry Cavendish (1731-1810)," TheLibrary 2 ( 1980): 281-92, on 2X4.

"WYc have only "Part I" of the catalogue of Dalrymple's library,
and it contains 7190 entries. Part II, containing books on nav igation
and travel, his specialty, might be even longer. A Catalogue of the
Extensive and Valuable Library of Boohs; Part I. Lair the Property of Alex.
Dalrymple, Esq. F.R.S. (Deceased). Hydrographer to the Hoard of
Admiralty, and the lion. Last India Company. Whirl/ Will lie Sold by
Suction, by Messrs. King if I. other. . . . on Monday. May 29, lfti'9, and
Twenty-three Following Days, at Twelve O'clock (London, 1 809).

ll5 Ellen B. Wells, "Scientists' Libraries: A Handlist of Printed
Sources," Annals of Science 40 ( 1 983 ): 3 1 7-89. on 338. 354, 362. and 370.

'"■Harvey has tallied books in Cavendish's catalogue by subject
according to whether they were published before or after 1 752. the year
Henry finished his university education. The results are not
meaningful in the way they are intended. The appropriate div ision for
assessing I lenry ( Cavendish's interests from the entries in the catalogue-
is 1783. when Lord Charles Cavendish died. The very different
approaches to the library of father and son are illustrated by the books
they bought bv subscription. By a recent count. Lord Charles
subscribed to 50 books over the course of his life. (His 50 subscriptions
were a large number. Only one of his contemporaries had substantially
more. Richard Mead w ith 210. William Stukeley had 60. William Jones
52. John Freind 50. Thomas Coke, earl of Leicester 50, and George
Parker, earl of Macclesfield 49.1 Tiv subject Lord ( Charles's subscriptions

Ho me

237

Chemical books are not listed under a separate
category but under natural philosophy, as are books
on most of Cavendish's other main interests, mechan-
ics, instruments, meteorology, and mineralogy. In
this same category are many books on medicine,
anatomy, and animal economy, but very few of
these books were published after Lord Charles
Cavendish died. Mathematics, the second largest
category, includes in addition to books on mathe-
matics, books on natural philosophy in which math-
ematics is used, such as Newton's Principia (all
editions) and Opt'tcks (all editions) and Robert Smith's
System of Opticks. Astronomy is well represented.
Lord Charles and Henry Cavendish were lovers of
rare books; they owned first editions of the classic-
works of science by Copernicus, Brahe, Kepler, and
others. In natural history, as opposed to natural
philosophy, Cavendish had only a slight interest; 117
what works he added in this category are generally
on mineralogy and geology. Not all books in the
catalogue are scientific. Editions of the classics with
Richard Bentley's signature are in the collection. 1,8
A category as large as mathematics is poetry and
plays, eleven hundred volumes, a subject on which
father and son evidently parted company. The
catalogue lists the works of Shakespeare, Dryden,
Congreve, Pope, Swift, Gray, Goldsmith, Gay,
Johnson, Sheridan, and other authors one would
expect to find in a literary library; there are some
works of poetry from the 1750s, but in the 1760s
and 1770s, the entries are of plays only, 119 and after
Lord Charles's death in 1783, only one book was
added to this category, an Indian drama, published
in 1790, two years before Cavendish published his
paper on the civil year of the Hindoos. 120 After Lord
Charles's death, when Henry alone added to the
library, there was no more poetry, theater, or fiction,
nor editions of classics, books of antiquities, or works
on architecture. 121 Henry had at most a passing
interest in history, and he did not keep this section of
his library current. By contrast, he had great interest
in books on voyages and travels, which he used in his
scientific work. The catalogue, we note, begins with
astronomy, mathematics, and natural philosophy,
the subjects that came first in Cavendish's life.

Often libraries are revealing of their owners
because of marginalia in their books. Cavendish,
however, rarely put a mark in a book; in the third edi-
tion of Newton's Principia, he penciled in some cor-
rections of numbers, and that is about all we have

found. Holding few surprises. Cavendish's library is
confirming, not revealing. It tells us that he was not
interested in literature and languages, 1 -'-' but that he was
interested in the physical sciences and mathematics.

Clapham Common

In the years 1782 to 1785, Cavendish was
pretty much constantly engaged in "removing my
house," as he told Joseph Priestley to excuse his
poor record as a correspondent. There is substance
behind this excuse, as suggested by the episode of
Charles (Allien. Within the space of three or four
years, Cavendish moved out of his father's house-
on Great Marlborough Street, into and out of a

correspond to his very broad range of interests: about 20 of them could
be regarded as historical, including antiquities, state papers, and
religious history; 15 of them were mathematical and scientific,
including natural history, and including editions of Bacon's and Boyle's
works. The remaining subscriptions are to books of travels, maps, law.
poetry, plays, and of miscellaneous other categories. Lord Charles's
subscriptions agree with the content of the Cavendish library in
general, according to his son's catalogue. Henry Cavendish subscribed
to 10 books. 9 of w hich were on science, mathematics, and travels. The
exceptional book to which Cavendish gave a double subscription would
seem to have been an instance of charity: Benjamin Clement. Sermons
on Several Subjects and Occasions (Wolverhampton, 1774), "for author's
widow." The one book to which both Henry and his father subscribed
was about science: Priestley's History of Vision, in 1772. R. V. and I'. J.
Wallis. Rrobiblrographv of British Mathematics and Its Applications, part 2:
1701-1760 (Newcastle upon Tyne: PHIBB, 1986): Index oj British
Mathematicians, part 3: 1701-1800 (Newcastle upon Tyne: I'HIBB.
1993). F. J. G. Robinson and I'. J. Wallis. Boot Subscription Lists. A
Revised Guide (Newcastle upon Tyne. 1975). I'. J. Wallis, completed and
edited by Ruth Wallis. Hook Subscription I .ists. Extended Supplement to the
Revised Guide (Newcastle upon Tyne: I'HIBB, 1996).

""But Linncaus was there, in nine volumes, the last two added
by Henry, in or after 178.S. The last book to which Henry Cavendish
subscribed was too late to enter the catalogue of his library: it was by
the late Thomas Garnett, with whom Cavendish had associated at
the Royal Institution. Popular Lectures on '/.oonomia: or. Lite Lavs of
Animal Life, in Health and Disease (London: published by the press of
the Royal Institution, 1802). There is the suggestion that in his later
years. Cavendish took an interest in the life sciences.

""Lacaita. Catalogue of the Library at Chatsvcorth :xvii.

"'With the one exception. Thomas Rowley, Poems, aith a
Commentary by Jer. Mi/les ( I .ondon. 1 782).

'-"Calidas. Saconlula. or the fatal Ring, an Indian Drama
(London. 1790). Not entered in the catalogue (it was too late) under
poetry and plavs but found in the Chatsworth library, with Henry
Cavendish's stamp, is the related work, lire Loves of Cdmarupa and
Cdmaluta. An Ancient Indian Idle, trans. W. Franklin ( I .ondon. 1 793).

'-''Two works on architecture bought by Henry Cavendish
might well have gone under different headings: John Smeaton's .1
Narrative of the Building and Description of the Construction of h.ddystone
Lighthouse and a translation of Vitruvius's Architecture.

'"'There arc a few dictionaries of translation, but not the
reference works of a person w ho lov es languages for their own sake.
Latin is as common as English in the books in Cavendish's library,
but that was a working language still, not an interest. Cavendish, ot
course, read Latin, and undoubtedly w ith ease. To keep up to date in
the sciences in which he worked. Cavendish bought books and
subscribed to journals in the modern European languages, especially
Trench, which he read and copied notes in.

238

house at I lampstcad, and into houses on Bedford
Square and on Clapham Common.

Clapham, Cavendish's new suburban address,
was similar to his old, I lampstead, and to a good many
other villages at about the same distanee from Lon-
don, inhabited by well-to-do professional people
with ties to London. He could see them from his
elevated perch at Hampstead, villages such as
Chelsea, Fulham, Putney, Hammersmith, and
Wandsworth. He chose Clapham or, to locate him
precisely, Clapham Common. 123

The move to Clapham Common was a parti-
cularly upsetting event in Cavendish's well-ordered
life, but it could have been much worse. Cavendish,
who in his daily life always had help and depended
on it, now had as his associate Blagden, who like
his librarian was the soul of order. Blagden relieved
( Cavendish of a great many of the details of his moves,
as we learn from Blagden's financial records. We
find there, for example, a bill from the summer of
17X5 for carpenter work on his, Blagden's, house at
Clapham Common, and also one for metal work
there; these misdirected bills can only mean that
Blagden was acting as Cavendish's agent. 1 -' 4 Other
bills for the w inter of 1 7S4 and the fall of 1785 are
for household furnishing for a large house, again evi-
dently ( Cavendish's. Items include enormous yardages
of green fabrics, damask, moreen, and silk lace for
the windows, chairs, and beds. 1 - 5 Like his house on
Bedford Square, Cavendish's house at (Clapham
(Common was decorated in the color green.

Despite Blagden's considerable help, Cav-
endish's move to Clapham (Common left his sci-
entific work in disarray. Because of the need for
repairs on the new house, (Cavendish and Blagden's
planned scientific journey to Wales had to be
postponed by three weeks in June 1785. 1 -' 1 That
September, Cavendish refused an invitation to visit
Yorkshire, as Blagden explained to the host, John
Michell: (Cavendish "promises himself that plea-
sure sometime or other, yet he cannot spare time
for another journey this year, as it will give him full
employment till winter to bring his new country-
house of Clapham into order. He is but just
removed thither: cv all his pursuits are interrupted
till his books, instruments etc can be brought out of
the confusion in w hich they lie at present." 1 - 7 The
interruptions continued. In November, Blagden
wrote to Laplace that "Mr. (Cavendish will not
soon hav e another paper ready, his apparatus hav ing

Cavendish

been deranged by moving to another house, where,
however, he has /illegible/ conveniences for carry-
ing on his experiments to still greater perfec-
tion. " ,2S Cavendish had to bide his time while his
new house was arranged as a house of science. He
was fifty-three at the time of his move to Clapham,
and it was to be the place of his scientific
researches to the end of his life.

With his father's generous inheritance,
(Cavendish had the wherewithal to build a great
house or buy one or several and to live in a grand style,
but of course he did none of these things. Not
lavish estates with large households, for which he
had no use, but a well-built, ample but still modest
house (vacated by a failed banker, we are told) met
his needs. To buy it he needed only a tiny portion
of his inheritance. Clapham (Common was not a
retreat for the aristocracy; no other Cavendishes
lived there, no Russells, no Manners. According to
a contemporary map identifying the seventy-four
houses on (Clapham (Common by their occupants,
only (Cavendish was addressed as the "Rt. Hon.,"
and only one other person had a title, a Lady Tibbs;
the others were simply "Mrs." or "Esq." 129
Cavendish stood out for his rank and his wealth, but
his house, household, and expenditure were in line
with that of the neighborhood.

,:i Hcnry Cavendish to Joseph Priestley, 20 Dec. 17X4. draft,
Cavendish Mss, New Correspondence; in Joseph Priestley, A
Scientific Autobiography of Joseph Priestley (1133-1804), ed. R. I-;.
Schoficld (Cambridge. Mass.: MIT I'ress. 1966), 239-40, on 239.
Villages comparable to Hampstead included Greenwich, Stoke
Newington, Highgate, Camberwell, Dulwich, and Twickenham.
Thompson, Hampstead, 26. From his new location. Clapham
Common, Cavendish used some of these villages for taking bearings:
the Observatory at Greenwich, a church in Highgate. a house on
Camberwell, Henry Cavendish, "Hearings," Cavendish Mss.

'-■'"Carpenters Work Done for I)r Blagden at His House at
Clapham." submitted by the firm Hanscomb Fothergill. The dates
of this work fall between August and November 1785. There is another
bill from the same period for metal work on the house, submitted by
Thomas Charles. Gloucestershire Record Office, I) 10X6, F 153.

l25 Bills submitted by (Juinton Kay for purchases and repairs in
October and November 17S4 and in September. October, and
November 17X5. Gloucestershire Record Office. I) 1086, F 153.
Blagden himself was moving, from King's Road to Gower Street, so
the bills for his expenses and those for Cavendish's are mixed
together in Blagden's papers and could be confused for one another.

'-'■Charles Blagden to Mr. Lewis, draft. 20 June 1785. Blagden
Letterbook, Vale.

'"Charles Blagden to John Michell. draft, 13 Sep. 1785, Blagden
Letterbook. Vale.

'-'"Charles Blagden to I'. S. Laplace, draft. 16 Nov. 1785, Blagden
Letterbook. Royal Society.

' -"'"Perambulation of Clapham Common 1800. From C. Smith's
'Actual Survey of the Road from London to Brighthelmston.'"
British Library.

Home

239

Grant AJimJ\t.
Cotton Etq

MTSamlrr

^EonMCaxmduk

PLATE VIII. Map of Clapham Common. Cavendish's house is on the left side of the common, fourth house from the top. "Perambulation of
Clapham Common 1800. From C. Smith's 'Actual Survey on the Road from London to Brighthelmston."' The Chronicles of ClaphamlCUtphatn Com-
man/. Bring a Selection from the Reminiscences of 'I nomas /'arsons. Sometime Member of the C.lapham Antirjiiiiriim Society (London: printed privately by A.V.
Huckle & Son. Ltd.. The Ramsdan Press, 1929), opposite page 1 12. Reproduced by permission of the Bodleian Library.

240

Clapham Common was described in a
survey of" 1 7JS-+ as "a very large straggling village,"
"pleasantly situated," and containing "many
country seats belonging to the gentry and citizens
of London." South of London, Clapham Common
stood on a low hill overlooking the Thames, four
miles from Westminster Bridge, with daily coach
service into the metropolis. Good roads made it
possible for Clapham inhabitants to go to London
by way of London Bridge, do business from one
end of the city to the other, and "without being
any further from home" return by Westminster
Bridge," completing a triangle. 1 " 1 " Lysons, in his
survey published a few years after Cavendish's
move, said that the population of Clapham had
increased faster than that of any other parish he-
had examined. In 17SS the population was 2,477;
four years later it was about 2,700 with an average
often new houses going up each year. 1 ' 1 ' Clapham's
draw was its magnificent common, which was
described to Cavendish as "the most beautiful, the
most healthy and highly improv ed spot of land, not
only round the metropolis, but perhaps in the
kingdom." 1 ;J This was an interested developers
hy perbole, but the appeal of the common to city
dwellers like Cavendish was strong. Bankers,
merchants, and other well-to-do Londoners built
big houses, often second houses, facing the
common. The feel of the common is captured in a
print from the time, 1784. Evoking pastoral calm
and quiet, in the foreground it shows footpaths, a
man w ith his dog, a cow, and in the distance across
the Long Pond, the new parish church and several
substantial houses. ( The cow in the print illustrates
the only story to have come down in which
Cavendish appears as a man of spontaneous action,
a hero. I le is said to have saved a woman who lived
at Clapham from the attack of a mad cow, causing a
sensation at Clapham where Cav endish was known
to go to lengths to avoid female encounters. 1 Vi )

Clapham Common had not always been
that attractive. Not many years before Cavendish
arriv ed there, this triangular piece of ground of ov er
two hundred acres had been a morass with
impassable roads. By means of a subscription from
the inhabitants, the wilderness had been trans-
formed into highly desirable residential property.
Drains were installed, paths were laid, and a great
many trees, English and exotic, were set out. The
energy and vision behind the public works were

Cavendish

provided in considerable measure by the Clapham
Common developer and resident Christopher
Baldwin, with whom, as we will see, Cavendish
was to have relentless and unpleasant business
dealings. Baldw in was justice of the peace, an office
he used together with personal influence to pursue
his schemes for Clapham. 134 The result was what
Cavendish saw from his house, a pleasant v ista of
ponds, mounds, groves of horse-chestnuts, poplars,
gorse thickets, pasture, and cow s.

Clapham Common would become a park,
but when Cavendish moved there, the parish still
paid a bounty on hedgehogs and polecats. If in ways
Clapham was still countrified, it was nonetheless
thoroughly civilized. The men who went daily to
work in the city or Westminster could leave their
families and possessions behind, confident cif their
safety," 5 and at night they could sleep in peace owing
to the lighting and the watch. Although there had
long been lighting and a watch at Clapham, it was
only in 1 7X4. just at the time Cavendish moved
there, that trustees were appointed by an act of
parliament to organize the lighting and watch of
the streets of Clapham and of the roads leading to
it. Cavendish and his neighbors were protected by
a dozen or so armed men, who from dusk to dawn
manned watchboxes w hen they were not patrolling
the roads between them. Misdeeds at Clapham
Common w ere few and usually minor: lead was stolen
or a duck or a pig but rarely was anyone robbed by a
highw ayman. 1 Other aspects of civilized life at Clap-
ham, such as buying land for w idening a road, exam-
ining sewers, and regulating fines in lieu of serving
a church office, were taken up in v estry meetings. 137

'"■Christopher Baldwin to Henr> Cavendish, .i May 1784,
"1 7X4-1 7W>. II. Cavendish & C. Baldwin. Correspondence re Sale of
Land." Devon. Coll., 86/comp. I.

11 Daniel Lysons, The Environs of London: Being mi Historical
Account of the Towns, Villages, and Hamlets, within Twelve Miles o) That
Capital, vol I: County of Surrey (London, \ 7')Z), 169.

' '-'Baldwin to Cavendish. May 17S4.

"'This story came down secondhand to Wilson from Mrs.
William Herbert, the then occupant of Cavendish's former house at
Clapham Common. The rescued woman was said to he Mrs. Keer.
who was no longer living. Wilson. Cavendish, 17H. There is possibly
more to this story: the cow could have belonged to Cavendish, w ho
had three at the time of his death. "Mr Cavendish's Kxccutorship
Agenda." Dev on. Coll.

'•"Lysons, Environs of London 1:154.

'•' 5 E. M. Forstcr, Battersea Rise (New York: Harcourt, Brace.
1956), 5.

''''Cavendish is listed among the householders but not among the
trustees in "Watching and Lighting Trust," I'/C/ll. " The Minutes of
the Trustees for Watching and Lighting the V illage of Clapham cV
Certain Roads Leading Thereto." I 7Hf>— ] H02. Minet Library, London.

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141

PLATE IN. Plan of Drains at ( Clapham. Cavendish's house faces the Common at the bottom of the diagram. The separate building to the right is
evidently a greenhouse, formerly containing an outhouse, which Cavendish refers to in his notes on experiments on air. To the left is a basin that
becomes a pond, 7 1/2 feet deep, into w hich the drains from H and K run, and which is filled from the pipe EF, which probably comes from the pond
across the road in the Common. G is the valve for letting water into the pond. The other letters srand for: A. a drain sink; B. the gate to the kitchen
Harden; BO, a drain running from Mrs. Mount's house to the right of what Cavendish has labelled Mrs. Mount's wall; I), a well formerly supplying
the pantry or dairy. Water from A eventually runs into a ditch in the field behind the house, and from there it is conducted to the "lane." presumably
Dragmirc Lane, which bounds Cavendish's property. Next to the pond is a sundial, w hich Cavendish used as a marker in taking measurements of
the basin. Cavendish refers to his walled "court yard," but he does not indicate its location. This diagram was probably draw n up in connection with
renovations ( lavendish made before moving into the house. "Plan of Drains at Clapham & Measures Relating to Bason," ( lavendish Mss. Misc.

In 1905 Cavendish's house at Clapham Common —
it had come to be called "the Cavendish House" —
was pulled down and the estate sold to be replaced
by rows of red-brick villas. At a sale near the end of
its life, the house was described as "a capital family
residence with a suite of well-proportioned recep-
tion rooms, elegant drawing room, noble dining
room, handsome library, morning room and billiard
room, a large conservatory and 17 bedrooms." The
grounds were "enriched with stately timber of oak,
cedar, beech, fir and cypress, laid out with a terrace
walk, lake and summerhouse." In addition there
were a kitchen garden, greenhouse, orchid house,
aloe-house, and vineries. Cavendish would have
been hard-pressed to recognize this showy,
sprawling, stuck-on structure as having once been
his. Its subsequent owners had had very different
taste and had put the house to vers' different
purposes. In 1833 it was bought by a developer,
who added a big reception room, another servants 1
wing, and the terrace fronting the garden. Thirty
years later it was bought by an art patron, who
enlarged it to hold a splendid collection of con-
temporary paintings. By imagining these accretions

gone and the white stucco laid over the original red
brick removed, the central block can just be made
out in late photographs of the house. This well-
proportioned eighteenth-century country house
was the house that Cavendish bought. 138

Cavendish's house was located near the
southeast corner of the common, a good w ays from
Clapham village. We get an idea of the shape and
arrangement of the house from a rough sketch in
Cavendish's hand of the layout of the drains. The
house faced northwest with its long dimension

These minutes give a good idea of the measures taken for the security
of life and property at Clapham, as do, in detail, " The Minutes of the
Sub-Committee for Watching & Lighting of the Village of Clapham is;
Certain Roads Leading Thereto." 1 7Sf>— I <S(»2, Minet Library, London.
Extracts from the latter are published in R. tie M. Rudolf, "The
Clapham Sect," in Clapham unrl the Clapham Sect, ed. E. Baldw in
(London: Clapham Antiquarian Society, 19271. 89-142.

1,7 The minutes of these meetings show that Cavendish did not
take an active part. His one appearance in the minutes was his
nomination and appointment for a year as "hcadborough." Entry for
9 Apr. 1798. "Clapham Vcstrv Minutes 1752 to 1798." Greater
London Record Office. P 9S/TR1 1/6.

l38 Cavendish was the second owner of the house; the first, Henton
Brown, was a banker whose business failed, according to Eric E. F.
Smith, Clapham (London: London Borough of Lambeth. 197(>), 78.

242

parallel to the road bounding the common, and
access to it was by a circular drive from the road.

Cavendish made alterations in his Clapham
house for privacy and for science, if the two can
meaningfully be separated. I le is said to have had a
back stairs built because he was annoyed by
encountering a maid with a broom and pail on the
existing stairs. 139 The conversion of a conventional
eighteenth-century house into Cavendish's work-
place left a memorable impression on his contem-
poraries. Little of the house was reserved for comfort,
as the rooms were given new functions; for example,
upstairs. Cavendish outfitted rooms for an astronom-
ical observatory, complete with a "transit-room," 14 "
and downstairs, he made over the drawing room
into a laboratory and an adjacent room into a forge.
The lawn had a wooden platform from which
Cavendish climbed a large tree to make scientific
measurements. M1 "The whole of the house at
Clapham was occupied as workshops and labora-
tory," the noted London instrument-maker John
Newman recalled. 14 - Another recalled that "it was
stuck about with thermometers, rain-gauges, etc." 141

People who entered Cavendish's house at
Clapham Common reacted to "its desolate
appearance, and its scanty and mean-looking
furniture," 144 according to Cavendish's younger
contemporary John Barrow. A house so given over
to scientific purposes no doubt could leave a
chilling impression with some people, but Barrow's
hearsay needs qualification. It may be impossible
now to know if Cavendish's house was scantily
furnished by the standards of the day, but it
definitely was not meanly furnished. Before
moving in. Cavendish bought a costly drawing-
room suite that included ten inlaid satinwood
cabriole elbow chairs, a cabriole sofa to match, and
a pair of inlaid satinwood pier tables with leather
covers.' 45 This furniture along with some of the
other contents of the house were listed by an
auctioneer as "modern" furnishings of a
"professional gentleman," containing "rich cut
glass and china, in table and tea services, bronze
chimney ornaments, paintings and prints, elegantly
framed . . . Creeian sofas and lounging chairs,
French and festoon window curtains . . . Brussells
and Kidderminster carpets. " ,4( '

To take care of these furnishings and to do all
the other tasks of running a house. Cavendish
employed a staff of seven domestic servants: a

Cavendish

housekeeper, a housemaid, a cook, a gardener, a
coachman, and two footmen. Because his house was
not ordinary but a place for doing science, Cavendish
had an additional servant who was not ordinary, a
mathematical instrument-maker, whom he paid
much more than the others, sixty-five pounds a
year. As Cavendish's way of life did not change
over the twenty-five years he lived in the Clapham
house, neither did the complement of servants. 147

Land Developer

In his survey of London in 1792, Lysons
said that the improvement of Clapham Common
owed to the "good taste and exertions of
Christopher Baldwin Ksquire, who has resided
many years in the spot." Proof of the improvement,
Lysons said, was Baldwin's recent sale of fourteen

''''Wilson. Cavendish, 170.

'■"■"Transit-room" at Cavendish's Clapham Common house
appears on the map in William Roy. "An Account of the
Trigonometrical Operation, Whereby the Distance between the
Meridians or the Royal Observatories of Greenwich and Paris Has
Been Determined." /'7'XO (1790): 1 1 1-270. on 261.

'"" These details were eolleeted by Wilson from Mrs. William
Herbert and from another Clapham resident. Dr. Sylvester. Wilson.
Cavendish, 164.

"-'Ibid., 164.

'■"This quotation was from a Fellow of the Royal Society . [bid.,

164.

'■"John Harrow. Sketches of the Royal Society and Royal Society Club
(London. 1849), 1 50.

l4S "About Purchase of House & t urn at Clapham," 1785.
Devon. Coll., 86/comp. 1. This packet contains a list of the
satinwood chairs and related furnishings, "Sundry Drawing Room
Furniture etc. of Wm. Robertson's Ksqr. Appraised to Cavendish
Ksqr. 1 1th June 17X5."

141 The catalogue lists six four-poster beds and two of the sofa
type. The beds and relared furniture were covered in green, and the
Venetian blinds were evidently green, too. (The prevalent color
green reinforces our belief that the bills for furnishings in Blagden's
papers refer to Cavendish's house at Clapham.) The catalogue also
lists over fifty cushioned chairs made of a variety of w oods: rosewood,
satinwood. and mahogany, and covered with red and yellow morocco
(a departure from monotone green). Throughout the house, the
wood was predominantly mahogany. A Catalogue oj tin Assortment of
Modern Household Furniture . . . which W ill Be Sold h Auction In Mr:
Squibb, at His Great Room Seville Passage, Saville Ron: on Wednesday,
December 5, 1810, and Two Following Days, at Twelve O'clock. 'This
catalogue is incomplete, since only part of the contents of
Cav endish's house at Clapham was taken to the place of this auction.
Saville Row. part being taken to Swift's Auction Room. "Mr. Swift's
Account with the Executor of Henry Cavendish Esq. Deceased." 26
Jan. 1H11. In the packet "About Purchase of I louse is; Turn, at
Clapham." 17X5, is "An Inventory," w ith notations by Cavendish, "of
Fixtures Belonging to Messr Collinson and Tritton of Clapham in
Surry to Be Valued to the Purchaser of the Estate, May 13th, 1732,"
Devon. Coll.. X6/comp. 1.

'■""Account of the Number of Persons Residing in the Parish of
Clapham . . . Dtd IX Feb. 1788," Greater London Record Office, P
95/TRI 1/72. "Wages Due to the Servants at Clapham and in
Bedford Square," 1810, Devon. Coll.

Ho nit'

243

acres of land close to his house for the steep price
of £5,000. ,4fi Lysons gave the amount of land
incorrectly — it was fifteen acres, not fourteen — but
the price was right. The unnamed buyer of this
piece of real estate was, we know, Henry Cavendish.

Baldwin was a merchant and West Indian
landowner who was interested in some of the same
things Cavendish was. Baldwin was well known to
the "amateurs of agriculture as a zealous promoter"
of agricultural science. 14 '' Beyond that, Baldwin had
a general curiosity about science. Shortly before
doing business with Cavendish, he had assisted
Benjamin Franklin in experiments on stilling
waves on a pond at Clapham Common. Baldwin
was a member of the Monday Club, 150 as were
many men of science, including Cavendish, who
was a member at the time he bought the property.
Perhaps it was through this scientifically oriented
club that Cavendish learned of Baldwins
undeveloped land at Clapham Common in the first
place. An early letter of Baldwin to Cavendish
began with a cordial reminder of their connection.
With reference to the experiments on air that
Cavendish was currently making, Baldwin wished
that "among your other learned & very curious
investigations in our atmosphere, you would tell
me when I may safely begin hay-making, since you
are interested in the attempt." 151 This familiarity
was a disastrous tack to take with Cavendish. The
business dealings of the two men were to prove
long, difficult, and acrimonious.

Well over a year before moving to his new
villa at Clapham Common, Cavendish had ap-
proached Baldwin about the land, letting him
know of his interest in buying fifteen or twenty
acres from him. At first Baldwin was not tempted
and suggested to Cavendish other landowners in
the area he might approach. For a time Cavendish
considered buying a farm, but then he came back
to Baldwin. The land in question was three fields,
totaling fifteen acres, bordering on Clapham Com-
mon, next to Baldwin's house and extending behind
it. Baldwin, now agreeable, began to speak of the
"market price' of his prime real estate, a piece of the
diminishing "front land" on the common. His was
not just any land, and it could no more be sold by the
acre than could land in London and Westminster. 152 .

Among Cavendish's scientific manuscripts
is a mathematical study of musical intervals, on the
back of which is the draft of a letter. Although the

letter is undated and unaddressed, the year is
clearly 1784 and the recipient clearly Baldwin: "I
forgot to ask you yesterday where you would have
me return the plans you sent me. I would have told
you yesterday how much I would give for the
estate had it not been that it is so much less than
what you said you had refused that I thought it to
no purpose. If however you have a mind I will let
you know what I think it worth & at the same time
as I hate hagling will tell you the utmost I will give
for it but in that case you may depend upon it that
I shall not offer any more." 153 Being uncertain of
the value of the land. Cavendish wrote to Baldwin
again that all he could say was that "if you arc
willing to take 5,000 £ for it I will give it though I
shall be almost ashamed to own how much it cost
me but I cannot by any means think of giving more
than that." 154 Baldwin asked for £5,650, which he
claimed was £1,2H0 below the market value as
established by what builders had offered him for
the land in the past. Rich as Cavendish was,
Baldwin implied, it would be nothing for him to
come up with the difference, only a few hundred
pounds. Trying flattery again, Baldwin said that
Cavendish's offer, even though it was insufficient,
expressed the "gentleman and the noble blood of a
Cavendish." 155 Having told Baldwin that he did not
haggle, Cavendish now proved it: "I did not make
you the offer of £5,000 without due consideration
& a resolut. not to give more than that & therefore
cannot consent to make any addit. to my former
proposal." Upon this note of finality, Baldwin
stepped down, agreeing to the £5,000, Cavendish's
original offer. 15 ''

Given that there was an agreement in writing
between buyer and seller, the closing of the deal

l4f, Lvsons. Environs of London 1:159-60.
'■•"Ibid., 159.

|50 Verner W. Crane, " The Club of Honest Whif;s: Friends of
Science and Liberty." William and Mary Quarterly Z5 (1966). 210-33,
on 215.

'"Christopher Baldwin to Henry Cavendish. 15 June 17H4.
Devon Coll., 86/comp. 1.

'"Baldwin to Cavendish, 3 May 1784.

'"Henry Cavendish to "Sir." draft, on the back cover of Henry
Cavendish, "Musical Intervals," Cavendish MssVI(a): 28.

'"Henry Cavendish to Christopher Baldwin, draft, nd. /reply to
letter of 3 May 1784/, Devon. Coll., 86/comp. 1.

'"Christopher Baldwin to Henry Cavendish, 2 June 1784,
Devon Coll., 86/comp. 1.

IS4 Henry Cavendish to Christopher Baldwin, draft, n.d.;
Christopher Baldwin to Henry Cavendish. 7 June 1784. Devon.
Coll., 86/comp. 1.

244

Cavendish

should have been straightforward, but it was not.
Three weeks later Cavendish had not yet reeeived
Baldwin's deed of purchase and documentation of
tide. "It is so very inconv. to me to wait so long,"
Cavendish complained, and he told Baldwin to get
after his lawyer. Baldwin responded that it was
Cavendish's lawyer, Thomas Dunn, w ho was causing
the delay, besides which, the "dilitaryness of the gent 111
of the law is proverbial." for himself, Baldwin had
plenty of "patience." Baldwin's wordiness did not
help matters. "I know you dont like long letters,"
Baldw in w rote in a postscript to Cavendish. 157

In his twenty years of residence at Clapham
Common, Baldw in newer knew of anyone having
difficulty selling land there — "til now." Dunn believed
that Baldwin was causing the difficulty by not
being forthright with the people holding mortgages
on his land, 1 '* and on his ow n he proceeded to get
releases of claims on the land by parties who had
court judgments against Baldwin. As it turned out,
the purchase money of £5,000 was exhausted in
paying off the mortgages and encumbrances on the
land, Baldw in receiving a mere residue of £166 for
his land and his trouble. On 2 November 17K4,
Cavendish agreed with Baldwin for the absolute
purchase of the land on Clapham Common.

for a year after the sale, there was a break
in Cavendish and Baldw in's correspondence. Then
a new conflict arose concerning a half acre, a
narrow strip at the edge of the land Cavendish had
just bought. It was where Baldwin had extended
his property a little w ay into a lane leading off the
common. Cavendish wanted to settle this business
with Baldwin promptly, but he could not; when
Cavendish returned from a trip into the country,
Dunn told him that Baldwin wanted £60 for the
legal expenses he was out. Dunn told Baldwin's
lawyer, who had advised Baldwin to accept a lower
figure of £40, that Cav endish would nev er pay him
£60 but that he might take him to court to force
him to convey the property. "I hope I shall never
have any business to transact with such another
man as long as I live,""'" Dunn told Cavendish.
Baldwin complained to Cavendish that Dunn did
not mind damaging Baldwin to save "a little matter
to you." Baldwin claimed he was actually out £120
for the closing arrangements, but if Dunn was to be
believed. Cavendish would file a bill in Chancery
against him if he would not take £40, requiring
Baldw in in turn to file an action against Cav endish

to try to recover the rest of his expenses. Baldwin
could not believe that Cavendish wanted to "go
through all this" for a "slip of land.""' 1

The dispute ov er the £40 w as not vet settled
when another arose. Dunn had heard that the
people of Clapham planned to pull down all fences
on the common. Baldwin, he said, knew of the plan.
If this was so. Cavendish "must not give him a
farthing for the piece of ground," w hich encroached
on the common. I Iearing of this, Baldwin wrote to
Cavendish: "In my whole life I never was so
heartily tired of any thing as I am of the unmeaning
correspondence into which I have been drawn by
you and your attorney. ... I am buried in letters
founded in error and ignorance." Baldw in was not
going to accept £40, and it was not true that the
people of Clapham were going to pull down the
fences. It was true, Cavendish said, and he told
Baldwin that he was informed that the people of
Battersea, the parish neighboring Clapham,
planned to tear down the fences on their common
unless the owners paid them a composition.
Cavendish said he was "so confident" of the
information he had received — its source, whom he
did not name, was an owner of land next to
Cavendish's — that he was no longer prepared to pay
Baldw in the £40, but only £40 less the composition.
It was up to Baldwin to discover the composition
the vestry would demand. Baldwin warned
Cavendish not to stir up the people of Clapham bv
spreading the idea of tearing up the fences or else
he could lose part of the garden of his new house
there. Cavendish replied that if Baldwin did not
accept his offer, £40 less composition, and make
ov er the rights to the property in two or three days,
he would take it as refusal and act accordingly. ">-

'''Henry Cavendish to Christopher Baldwin, draft, n.d.;
Christopher Baldwin to Henry Cavendish. 7 June I7K4. Devon.
Coll.. 86/comp. I.

'"Henry Cavendish to Christopher Baldwin, draft, n.d.;
Christopher Baldwin to Henry Cavendish, .5 July 17X4. Devon. Coll.,
86/comp. 1 .

'^Baldwin to Cavendish, i July 17X4: Thomas Dunn to Henry
Cavendish. 7 July and 27 Aug. 17X4 and "Friday," Devon. Coll..
86/comp. 1 .

''""Abstract of the Title . . .," Devon. Coll.. L/38/78.

""Christopher Baldwin to Henry Cavendish, 7 July /1 7X5/; Henry
Cavendish to Christopher Baldwin, draft, n.d. /July 17X5/; Thomas
Dunn to 1 lenry Cavendish. 6 Sep. 1 7X5. Devon. ( loll., 86/comp. 1 .

"'Christopher Baldwin to Henry Cavendish, 1°. Sept. 17X5,
I )ev on. ( loll., 86/comp. 1 .

" "Thomas Dunn to Henry Cavendish. 6 Teh. 17Xo; Christopher
Baldwin to Henry Cavendish. 22 Teh. 17X6; Henry Cavendish to

Copy rig hied material

Home

245

Cavendish asked for a "direct answer," but
Baldwins answer was anything but direct. He
asked a question, which was about Cavendish's
intention to build a fence between their properties.
Even before Cavendish had bought the fifteen
acres, Baldwin had sent him "Hints for Con-
sideration," advice to Cavendish about building
fences and foundations. 163 Cavendish had not
responded. Later, after Cavendish had bought the
land, Baldwin told him that his fences were ruined,
allowing cattle to break in from the common and
enter Baldwin's garden from Cavendish's fields.
Baldwin ordered Cavendish immediately to put up
the fence between their properties, as Cavendish
had proposed to do. He would have put it up long
before. Cavendish said, if he had not waited to
settle the dispute about the piece of land taken
from the common. M "I shall observe my agree-
ment about the fence but will not be prescribed to
about it nor bear your delays or cavils." Baldwin
was to come to Dunn's on Wednesday or Thursday,
when Cavendish would be there to execute the
deed; otherwise, it would be too late and Cavendish
would give him nothing for the land. When
Baldwin wrote back asking Cavendish what he
meant by saying he would observe his agreement
about the fence. Cavendish was driven to the limit.
The correspondence between Cavendish and
Baldwin came to an end with a flurry- of letters,
four letters passing between them on one day, the
first Saturday in April 1786. Cavendish wrote: "I
can not at all conceive what is the cause of this
behavior whether you have any private reason for
wishing to delay the agreement or whether you
distrust my honour about the pailing & wish to
make some further conditions about it. If the latter
is the true cause you may assure yourself that I will
never submit to make any such conditions or ex-
planation with a person who distrusts my honour.""' 5
The papers were signed a few days later, legally
conveying the property to Cavendish. 1W ' The whole
transaction had taken two years.

Baldwin had tried to lighten his negotiations
with Cavendish with a learned ((notation. He gave up,
making a chemical pun of his defeat: "attick salt does
not easily unite with matters of business." 167 Doing
business with Cavendish was so straightforward
that Baldwin never grasped it. Cavendish did not
bargain, which would have required social skills he
lacked or chose not to use. His way of doing

business was to inform himself of value and make a
fair offer, which the seller was then to take or leave.

Cavendish's way was not Baldwin's, which
was to try to gain advantage by bargaining, pleading,
and bluffing. All of this Cavendish simply took to be
Baldwin's evasions, with which he had no patience,
and yet over the whole course of the transaction.
Cavendish was patient. I le did not break off negotia-
tions, even when, as he saw it, there was nothing to
negotiate. He persevered despite their disagreement
over price, their disagreement over lawyer fees, his
lawyer's doubts about Baldwin's honesty in dealing
with his creditors, his lawyer's suspicions that Baldw in
was concealing knowledge of Clapham's plans to tear
down fences, their argument over the fences to be
built, and Baldwin's delays. He waited out Baldwin.
I le told Baldwin what he wanted, and if Baldwin
complained about it, he did not argue but said what
he wanted again, this time more firmly. It worked; for
in the end, Cavendish got what he wanted, the land,
with clear title, and he got it at his price.

Baldw in misjudged Cavendish from the start,
and because he did, he provoked Cavendish into
exposing a side of his personality. Baldwin thought
that money was the issue throughout, and for him
no doubt it was, especially given his large debts.
But for Cavendish, the difference between £40 and
£60 or the cost of a fence was of no financial conse-
quence. The point was correct procedure. Property
transactions were to be conducted fairly, in accor-
dance with property law, business customs, and
knowledge of local conditions, without relation to
what one privileged party could afford and one-
needy party might wish for. After an agreement
was reached, keeping one's word was a point of

Christopher Baldwin, draft, n.d. /after 22 Feb. 1786/; Christopher
Baldwin to Henry Cavendish, 27 Feb. 1786; Henry Cavendish to
Christopher Baldwin, draft, n.d. /after 27 Feb. 1786/, Devon. Coll..
86/comp. 1 .

" 'Christopher Baldwin to Henry Cavendish. Midsummer's Day.
1784. Devon Coll., 86/comp. 1.

"''Christopher Baldwin to Henry Cavendish, 8 Feb. /1 786/:
Henry Cavendish to Christopher Baldwin, draft, n.d. /on or after 8
Feb. 1786/, Devon. Coll.. 86/comp. 1.

"' s Christopher Baldwin to Henry Cavendish. Mar. 178d. Satur-
day /l Apr. 1786/, Saturday /l Apr. 178f>/: Henry Cavendish to
Christopher Baldwin, drafts, 1 Apr. /1786/, n.d. /I Apr. 1786/, Devon.
Coll.. 86/comp. 1.

"■'■Christopher Baldwin to Henry Cavendish. "Lease for a Year."
5 Apr 1786; "Release of a Piece of Land on Clapham Common," 6
Apr. 1786. At the same time, Baldw in gave up all claim to the original
fifteen acres. Christopher Baldwin to Henry Cavendish. "General
Release." 6 Apr. 1786. Dev on. Coll., L/38/78.

"-Baldwin to Cavendish, 3 July 1784.

246

Cavendish

honor. Baldwin's single worst mistake was to doubt
the word of Cavendish.

In his correspondence with Baldwin, Cavendish
said nothing of his reasons for buying the land.
Baldwin thought that Cavendish intended to build
on it for himself, and perhaps at first he did, but in
the middle of their dealings, Cavendish moved
into an existing house on another part of the
common. Later Baldwin thought Cavendish in-
tended to rent the land, in which case he asked to
be the renter, but Cavendish turned him down. 168
Cavendish had bought an extensive, expensive parcel
of land, making him a dominant property ow ner at
Clapham Common, lie had made a good invest-
ment: at the time of his death twenty-five years later,
land on Clapham Common was selling for £500 an
acre, a price fifty percent above w hat he had paid."' 1 '
But land was not where Cavendish chose to invest
his money, and it was not primarily as an investment
that he bought Baldwin's fields at Clapham
Common. Clapham Common was to be his main
residence, the place of his scientific researches. By
owning a sizable piece of land fronting onto the
common, he could conceivably exert local influence
if he needed to. lint that was probably a side benefit
if it was a consideration at all. After Lord Charles's
death, I lenry ( lavendish had a legal analysis made
of his parents' marriage settlement. I le w as told
that he could "suffer recoveries" and thereby
obtain absolute power of disposal of the land or
stocks in question. We do not have the documents
that followed from this legal opinion, but we know
that I lenry Cav endish did pursue recoveries, and
the purchase of land was one possible route. 17 "

Whatever his motivation, Cavendish arrived
on Clapham Common as a developer. He promptly
rented Baldwin's former land to three builders at
£200 a year each. By the terms of their lease, they
were to spend at least £4,000 within four years to
build "good 6k substantial dwelling houses with
convenient stables coach houses" and to spend
another £6,000 within eight years for the same
purpose. When the buildings were "compleated to
the satisfaction" of Cavendish, the builders and
Cavendish would join in granting separate leases
for the houses provided that the rent was payable to

Cavendish and that it was not below a certain
amount. The separate leases were to prohibit the
building of a brick kiln — which made a terrible-
stench — on the premises and the use of any
buildings as public houses or shops "for carrying on
any noisome or offensiv e trade or business." 171 There
would be a proper tone, and the new residents living
across the corner of the common from Cavendish
would not disturb the quiet of his studies. Five long-
term leases agreeable to his conditions were granted,
w hich brought him a total yearly rent of £200. 172

Lltimately, the money that Cavendish paid
Baldwin came from other Cavendishes, and like
ev erything he owned, the Clapham Common prop-
erty was one day to be returned to other
Cavendishes. He assured his Cavendish patrimony
and his science by naming as trustees of his Clapham
Common estate his closest scientific colleagues in
London, Charles Blagden, Alexander Dalrymple,
and Alexander Aubert. They were parties to the
purchase of the land with the responsibility, which
would pass to their heirs, of protecting the
inheritance. That is what happened; in due time, in
1K27, the heirs of Cavendish's trustees discharged
their responsibility by transferring their trusteeships
to other persons, who held the Clapham Common
estate in trust for the biggest landowning Cavendish
of them all, the then current duke of Devonshire. 1 "

'"Baldwin to Cavendish, 3 May 17K4 and H Feb. 17K6;
Cavendish to Baldwin, draft, n.d. /on or after H Feb. 178f>/.

"•'in 1 HI 0 Robert Thornton sold his land on the common for
this price. T. C. Dale. "History of Clapham." in Clapham and the
Clapham Sect, pp. I -is, on p. 1.

""Henry Cavendish's legal analysis of his parents' marriage
settlement. Devon Coll., L/I14/74. From a list. "Deeds and Writings
Belonging to the Hon 1 * Henry Cavendish." we have the title of a
document concerning recoveries but we have not been able to locate
the document: "Bargain and Sale Inrolled in Chancery from Henry
Cavendish Esq. to Mr. Wilmot for Leading the Uses of Recoveries,"
11 Apr. 17.S4. Ibid.

171 "Henry Cavendish Esquire and Messrs Hanscomb, Fothergill
and Poyndcr Articles of Agreement for a Building Lease." I May
1791, Devon. Coll.. L/M/4.5.

,72 Four leases for buildings and land were signed in 1795, the
fifth, to two of the builders themselves, in 1K0.S. A sixth lease, in
1805, was for land only, and it went to the third builder. "Statement
of Leases Granted by the Honourable Henry Cavendish of
Messuages and Land at Clapham in Surry," Devon. Coll., L/34/10.

'""Abstract of the Title . . ." Henry Cavendish's brother,
Frederick, and after him the duke of Devonshire received rents from
the Clapham Common estates until they were sold in \XZ7. Devon.
Coll., L/16/20.

CHAPTER 2

Politics

Political fervor, like religious fervor, was
unwelcome at the meetings of the Royal Society.
The president Sir Joseph Banks took pride in
keeping a personal distance from all things having
to do with political faction: "I have never entered
the doors of the House of Commons," he told
Benjamin Franklin at the time of the American
Revolution, "& I will tell you that I have escaped a
Million of unpleasant hours & preserved no small
proportion of Friends of both parties by that
fortunate conduct." 1 But within every group,
however disinterested in politics in principle,
power can become an issue, a truth that would be
brought home to Banks the year after his letter to
Franklin on the subject of his political innocence.

The inevitability of politics in life would
not have been news to Lord Charles Cavendish.
When he changed the focus of his work from the
House of Commons to the Royal Society, he did
not move from a political life to one outside
politics. Rather, he moved to a social setting in
which he had more control: from a back bench
committeeman in parliament, he had become an
almost permanent member of the ruling council
and a frequent vice-president of the Royal Society.
Henry Cavendish did not directly participate in
national politics, but he found himself in the
middle of a political fight in the Royal Society that
reflected the political divisions of the nation at
large. The parallels between the Royal Society and
the monarch, court, ministers, and parliamentary
parties were perfectly obvious to the scientific
participants, who liked to point them out.

The Royal Society

In his History of the Royal Society, Charles
Richard Weld wrote that it was "painful" for him to
turn to the events of 1783 and 1784, and he would
rather have passed over them in "silence," but
duty forbade it. He then proceeded to give what he
regarded as an impartial account of the events of

the so-called "dissensions," which "turned the hall
of science into an arena of angry debate, to the
great and manifest detriment of the Society." 2

The dissensions originated, Weld explained,
in a widespread resentment of Joseph Banks, who
since the end of 1778 had been the elected
president of the Royal Society. A certain faction of
the membership was particularly unhappy with
Banks's conduct in the election of new members to
the Society, which took the following form. Fellows
wishing to elect a new member usually brought
him to one of Banks's Thursday morning break-
fasts. If Banks approved of him, the candidate
would then be invited as a guest to a dinner of the
Royal Society Club, at which Banks also presided,
where he would meet influential members. But if
Banks disapproved of the candidate, he would
urge individual members to blackball him at
balloting time. 3

For the good of the Society, Banks believed,
the members should bring in two kinds of persons:
men of science and men of rank. Like the
membership at large, the ruling council of the
Society contained men of both kinds, and here
again in the elections Banks made clear his likes
and dislikes, exposing himself to the charge of
packing the council with pliant friends. The result
of Banks's forceful interference in elections
revealed a pattern, so certain members thought,
which was a bias against men of science.

'Joseph Hanks to Benjamin Franklin, ° Aug. 1782, quoted in A
Hunter Dupree, Sir Joseph Hanks tintl the Origins of Science Policy
(Minneapolis: Associates of the James Ford Bell Library, University
of Minnesota. 1984), 15.

-Charles Richard Weld, A History of the Royal Society, 1 Mils.
(London. 1848) 2:151. This discussion of the Royal .Society's
dissensions is taken from Russell McCormmach, "Henry Cavendish
on the Proper Method of Rectifying Abuses." in Heyonrl History of
Science: Essays in Honor of Rot/erf E. Sihofield, ed. K. Carbcr
(Bethlehem. Lehigh Univ. Press, 1W0), 35-51. We acknowledge
permission by the Associated University Presses to use material from
this article.

'Weld, History 2: 152-54.

248

Cavendish

particularly men of the mathematical sciences, and
in favor of men of rank. Their dissatisfaction with
Banks came to a head in, as Weld termed it, the
"violent dissentions, foreign to matters of science,"
of 1783 and 17H4. 4

In Weld's account and in other historical
accounts of the dissensions, Henry Cavendish
receives only one brief mention, if any at all.
Passages from violent speeches are quoted at
greater or lesser length, but Cavendish is recalled
only for his seconding of a motion of approval of
Banks as president of the Society. 5 This, to be sure,
was the only time Cavendish entered the public-
record of the dissensions, but there w as much more
to Cavendish's involvement than this, as there
almost had to be given the stakes and the emi-
nence of Cavendish in the Society. At the height of
the dissentions, Charles Blagden, who at the time-
was both a scientific assistant to Cavendish and
personal assistant to Hanks, wrote daily letters to
Banks, which afford us a detailed account of
Cavendish's thoughts and actions.

To understand Cavendish's part in the
dissensions, we need to recall some of the
characteristics of the Cavendishes in politics with
which we began this biography. A contemporary
historian w rites of the Cav endishes:

Much was heard of the "great Revolution
families" — of w hom some of the proudest, as Sir
Lewis Namier lias pointed out, were in fact
descended from Charles II's bastards. These
families — above all, perhaps, the Cavendishes —
could not forget that their ancestors had, as it were,
conferred the crown upon the kind's ancestors, and
they did not mean to let him forget it either, for
they alluded to it in season and out of season. They
looked upon themselves as his creators rather than
his creation: one would almost say that they had
forgotten that the dukedom of Devonshire itself
had been established, less than a century earlier, by
the merely human agency of a king.' 1

Edmund Burke observed in 1771 that "No wise
king of Great Britain would think it for his credit to
let it go abroad that he considered himself, or was
considered by others, as personally at variance
with . . . the families of the Cav endishes." 7

(ieorge III, Burke also believed, was no
wise king. Whereas the first two Ceorges had had
to conciliate the families of, and to reconcile
themselves to the principles of, the Glorious
Revolution. Ceorge III could take for granted the
security of the dynasty. Upon acceding to the

throne in 1760, he immediately set about to break
the power of the old whig families. In fact,
although it was not entirely obvious at the time,
the whig ascendancy had come to an end. Marking
this historic turn was the resignation in 1762 of the
fourth duke of Devonshire; never again could the
Devonshire's assume that high office was their
birthright. At just this time, Henry Cavendish
entered the world of science; // he had desired a
life in politics, and //he had been adept at politics
as he was at science, he might well have turned
against his wishes and wisely chosen a life in
science all the same. We have an idea of the kind
of politician Henry Cavendish would have been
from his part in the dissensions of the Royal
Society. He would have been a politician of a very
recognizable Cav endish v ariety.

Devonshire House, the Piccadilly mansion
of the dukes of Devonshire, was the London
headquarters of the whigs.* 'The whigs of the
17fS()s. the so-called New Whigs, were libertarian,
passionately opposed to (ieorge Ill's policy on the
American colonies, and admiring of Charles James
Fox, the most implacable of (ieorge Ill's personal
enemies. 1 ' 'This whig leader and his king were in
fundamental disagreement about power: Fox
believed that power was properly exercised only
through the king's ministers, whereas (ieorge III
believed that his ministers were bound by loyalty
to uphold his policy, (ieorge III found unintel-
ligible Fox's doctrine that the king was to enjoy no
personal power, that he was merely to sit on the
throne, not to rule from it. In the ensuing
constitutional struggle between Ceorge III and
Fox and his allies, the government of the kingdom
was broughr to a standstill. The person of (ieorge
III was the political issue, as John Dunning's famous
resolution of 1780, which was favored by a

♦Ibid., 2:153, 170. Henry Lyons, The Royal Society, I660-IV40:A
History «/ Its Administration under Its (.hatters (New York: Greenwood,
1968). 198-99.

'Weld, History 2:162. Lyons, Royal Society, 213.

'■Richard Pares. Kin/; (Ieorge III and the Politicians (Oxford:
Clarendon, 1953). 58-59.

"The plural "families" was used by Burke because there was
more than one politically influential Cavendish family. In the sentence
quoted, Burke referred to several political leaders in addition to the
( lavendishes. Pares, Kin); deary ill and the Politicians, 59.

"Whisks arc the subject of Hugh Stokes, The Devonshire House
Circle (London: Herbert Jenkins, 1917).

''John Pearson. The Serpent and the Stag: the Saga of England's
Powerful and Glamourous Cavendish Family from the Age of Henry the Eighth
to the Present (New York: Holt, Rinehan and Winston. 1983), 12H-29.

Copyrighted maien

Politics

24')

parliamentary majority, asserted: "'That the influence
of the Crown has inereased, is increasing, and
ought to be diminished." 10 The years 1783-84, it
has been argued, witnessed the greatest political
crisis in Britain since the Revolution of 1688."

It was these same years, 1783-84, that
witnessed the dissensions of the Royal Society, in
which the president, Joseph Banks, was accused,
like George III, of desiring personal rule. The
regular business of the Society was brought to a
standstill. While Henry Cavendish's relatives,
above all his first cousin and chancellor of the
exchequer Lord John Cavendish, were actively
concerned with the constitutional crisis, Henry
himself was actively concerned with the crisis in
the Royal Society. Henry was, according to a
relative who was in a position to know, "very proud
of his family name," 12 and the nature of his activity
in the political affairs of the Royal Society was as
characteristically "Cavendish" as his slouching gait.
Just what this means we will take up later after first
discussing the dissensions of the Royal Society and
Cavendish's place in them.

The political crisis in the Royal Society
began with a disagreement between the president
and his council on the one hand and the foreign
secretary, the mathematician Charles Hutton, on
the other. Unlike the two regular secretaries of the
Society, the foreign secretary was not necessarily on
the ruling council. When Hutton was elected to his
office in 1779, he happened also to be an elected
member of the council, but after 1780, when the
dissensions occurred, he was no longer. The first
indication of the disagreement was recorded at a
meeting of the council on 24 January 1782, at
which time Hutton's responsibility and performance
were taken up. The one was judged onerous, the
other inadequate: Hutton, it was decided, had not
dealt punctually with the foreign correspondence,
his first obligation; he was also overworked and
underpaid, which seemed a likely reason for the
tardiness. The council resolved that in the future,
Hutton should not be expected also to translate
foreign articles and extracts from foreign books,
and in return he was not to fall behind in the
foreign correspondence. Hutton agreed to continue
on as foreign secretary with this new understanding.
Nothing more was heard of the matter publicly
until nearly two years later when, at a meeting of
the council on 20 November 1783, it was resolved

that the foreign secretary of the Society had to live
permanently in London. Hutton was professor of
mathematics at the Royal Military Academy of
Woolwich and so could not live in London. Two
members of the council, the astronomer royal,
Maskelyne, and one of the regular secretaries of
the Society Paul Maty, dissented from this move,
which was obviously directed against Hutton.
Hutton promptly resigned. At the ordinary meeting
of the Society on 11 December 1783, it was mov ed
that Hutton be formally thanked for his services as
secretary for foreign correspondence. Banks op-
posed the motion, which was vigorously debated.
The motion passed by a narrow margin, and Banks
duly thanked Hutton. At the following meeting,
on 18 December, Hutton delivered, and a secretary
read aloud, a written defense of his handling of the
foreign correspondence. Afterwards, a motion was
made and carried that Hutton had justified himself,
which again was attended by a vigorous debate.
The mathematician Samuel Horsley attacked Banks,
accusing him of infringing upon the chartered
rights of the Society. Horsley said he knew of
enough wrongs to keep the Society "in debate the
whole winter . . . perhaps beyond the winter." 13

The prospect of a winter of discontent,
spent in acrimonious debate, was abhorrent to
Cavendish, who regarded the serious scientific
purpose of the Society as inviolable. At this point
he became actively — if invisibly to all but a
handful of members — engaged in shaping the
outcome of the dissensions. His activity is reported
in letters Blagden wrote daily from London to
Banks at his country house.

It quickly became apparent that the person of
Joseph Banks was the issue. The debates, highly
personal in tone, turned on a scientific judgment.
The question the members had to answer was this:
had the Society been seriously damaged scientifically
by its president, Banks? To inform Banks, Blagden
delicately inquired into Cavendish's position on the
question. Naturally, Banks needed to know where the
Society's scientifically most eminent member stood.

'"Pares. King Ceotge 111 and the Politicians, 1 19-25. 134-35.

"John Cannon, The Fox-Sorth Coalition: Crisis of the Constitution.
1782-4 (Cambridge: Cambridge I'nivcrsity Press, 1969), x-xi.

' 2 Lady Sarah Spencer quoted in Stokes, Devonshire House
Circle. 315.

"Weld. History 2:154-60.

250

Cavendish

On Monday, four days after the stormy
meeting of the Royal Society, after dining at their
scientific club. Cavendish went with Blagden to his
home, where they discussed the troubles of the
Society. 14 That morning Cavendish had gone to see
William Heberden, and the two of them had
arrived at a common position. Blagden reported
that Cavendish and Heberden would support
Banks, but "just." While Cavendish did not
"absolutely refuse a vote of approbation" of Banks,
he would absolutely reject any resolution that, by
its wording, would seem to pass censure on
I Iorsley and his friends for what they had done in
the past. They had given no evidence of acting out
of any motive other than the good of the Society,
Cavendish said. Furthermore, the good of the
Society required of its members just such vigilant
scrutiny of their president and council. But
Cavendish did not mean for this watch to take the
form of debates during regular meetings, which
disrupted the scientific business of the Society. To
put a stop to the debates without denying the
members their rights. Cavendish proposed a
resolution, which he believed would be passed by a
very large majority, f rom dictation Blagden wrote
down the resolution and then read it back, to make-
sure of the wording:

That the proper method of rectifying any abuses
which may arise in the society is, by choosing into
the council such persons as it is supposed will
exert themselves in remov ing the abuses and not
by interrupting the ordinary meetings of the
society with debates.

Blagden did not think that this resolution would
have the result Cavendish expected of it. Horslev
would agree that it was the task of a new council to
remedy the abuses, but he would argue that for the
Society to be made aware of the abuses, the
debates must continue. Cavendish thought that
such an argument from 1 Iorsley would carry
weight, but there was an effective answer to it. For
example, the Society could inform itself of any
abuses by holding special meetings for the
purpose. Then if Horslev persisted with his
interruptions, the Society would be within its rights
to censure him. Blagden gave Banks his opinion
after this conference with Cavendish: the
resolution Cavendish ptoposed was probably the
best of any proposed so far, and if to it was added
another resolution to the effect that any motion
had to be announced at the meeting before it was

to be debated, the whole affair might be brought to
a speedy and favorable conclusion. 11 '

But Cavendish's resolution omitted all
mention of support for the incumbent president,
Banks, which was something less than Blagden and
Banks had hoped from him. Cavendish did not
even want to talk to Banks about past councils
because he found it awkward. With the help of
Blagden's prompting, however. Cavendish recalled
past presidents he had served under. Banks's
predecessor, the physician John Pringle, Cavendish
said, had acted like Banks and had given rise to the
same complaint about ineffective councils."'
Pringlc's predecessor, the antiquary James West,
was "King Log" (of Aesop's fable of the frogs who
desired a king to watch over their morals and were
thrown an ineipid log instead). But West's
predecessor, the astronomer and mathematician
Lord Morton, handled the affairs of the Society in
an unexceptionable way. Cavendish allowed that
Banks's method of choosing the candidates for
council was fair; but he blamed Banks for not doing
as Morton did, which was to "put in people who
would have an opinion of their own, without
agreeing implicitly with the President in every
thing." Cavendish believed that if his resolution
carried, it would mean that on election day there-
would be a contest. He wanted Blagden to reassure
Banks that he would support the "House list" on
election day unless it was "very exceptionable."
He also wanted Blagden to tell Banks that he did
not want to be consulted on the list beforehand, as
Banks hoped he would (for it would have tended to
forestall further criticism of Banks concerning the
scientific respectability of the council). 17

The day after he talked to Cavendish,
Blagden went to see Heberden. Heberden had not
only talked with Cavendish but also with Banks

|4 On Monday c\cnings. Cavendish ami Blagden generally dined
together at their club meeting at the George & Vulture, which we
assume is what brought them together on that Monday, 22
December 17H3.

l5 Charles Blagden to Sir Joseph Banks. 22 December 1783;
original letter in lit/william Museum Library; copv in BM(NII),
DTC3 171-72.

" Vet Banks's opponents professed to admire Pringle, at least in
certain respects, and wished Banks were more like him. Personality
and political temper, not consistency of argument, gave the
dissensions of 1783-84 their impetus. Weld, History 2:160-61.

"Charles Blagden to Sir Joseph Banks, 22 December 1783.
Charles Blagden to Sir Joseph Banks, Wednesday morning, 24
December 1783: original letter in Fitzwilliam Museum Library; copy
in BM(M1), D IC 3:176,

Politics

251

and with one of Banks's opponents, no doubt
I lorsley, and his opinion was settled. His opinion
was the same as Cavendish's: the proper method of
correcting abuses was to choose the proper council,
and Banks was fit for his office. To Blagden's
proposal of a vote of approval of Banks, Heberden
said that he would vote for it and that if it should
pass almost unanimously, the disturbances would
die down, but he objected to it on the grounds that
it would prompt a debate about Banks's conduct
and inflame the passions it was intended to quiet.
No "method," he believed, would prevent Horsley
from bringing motions from time to time. So from
Cavendish and Heberden, two highly respected,
senior members of the Society, Banks received the
same advice: let the Society affirm that power was
invested in the elected council and not in the
Society acting as a body any time it should choose,
nor, it went without saying, in the person of the
president, whoever he happened to be. 18

Blagden wrote to Banks twice the next day,
24 December. In the morning he wrote to say that
Cavendish was probably at his country house at
Hampstead. He did not want to go there, since it
would appear "too solicitous," and instead he
intended to go to Cavendish's townhouse. 14 Later
in the day Blagden wrote again, this time to say
that he had left a note for Cavendish telling of his
meeting with Heberden and conveying Banks's
wish that Cavendish would come to his house the
next day. Cavendish, finding the note, had then
called on Blagden to tell him that he could not go
to Banks's house. To this, Blagden wrote to Banks
that it was "possible" that Cavendish had set aside
the following day for doing experiments, but most
likely he wanted to avoid an "embarrassing
conversation" with Banks. Banks was to be
reassured that Cavendish was not "hostile" toward
him and wanted to remain on good terms with him.
It was only necessary that Banks allow Cavendish
to differ with him in opinion at any time "without
an open quarrel," which was to repeat what
Cavendish wanted of Banks in his dealings with
the council. 20

Blagden then turned their conversation to
the principal disrupter of the meetings of the
Society, Banks's enemy, Horsley. Blagden put their
conversation in quotation marks so that Banks
would have Cavendish's exact meaning. (Being the
only recorded spoken words by the reserved Henry

Cavendish, these quotations hold an interest of
their own.)

CAVENDISH: I did not expect any success from
the Drs negotiations [Dr. Heberden and, no doubt,
Dr. Horsley's]. But whatever violence they may
express, that is no reason against proceeding with
all moderation, as by such conduct the sense of
the Society will be ensured against them.

BLAGDEN: I wish you would see Dr. Hlorsley]
6v learn from himself the implacable temper
expressed; as I think you would then change the
opinion to which you seemed inclined when we
conversed last, that those gentlemen might have
nothing in view but the good of the Society.

CAVENDISH: I did not say they had nothing else
in view, but only that no proof yet appeared of
other motives.

At the end of their conversation, Cavendish came
around to Blagden's position: he, like Heberden,
would approve a vote of confidence in Banks, but
only if its wording gave no offense. With this,
Blagden declared himself highly satisfied with the
results of his mediation. 21 What temained to be
done was to bring the right members together to
determine a course of action.

The next day was a Thursday, ordinarily a
day on which the Society met, but this Thursday
was Christmas. Blagden did not take a holiday from
his politicking but made plans that day to see
Banks. 22 On Friday, Banks wrote to Blagden that
since his meeting with Heberden, at which he
learned that Heberden would not support any
motion that would suppress debate in the slightest,
he was forced to change his "plan" somewhat. Lest
his suppotters think him cold-blooded and
abandon the cause, Banks intended to come to
town on Monday with a modified plan. Blagden
was to summon certain persons to meet with him.
He would "strike while the iron is hot." 25

'"Charles Blagden to Sir Joseph Banks, 23 December 1783,
Fitzwilliam Museum Library-, Perceval H. 199.

'''Blagden to Banks, Wednesday morning. 24 December 1783.

^Charles Blagden to Sir Joseph Banks, 24 December 1783;
original letter in Fitzwilliam Museum Library; copy in BM(NH),
DTC 3: 1 77-79.

"Throughout the dissensions, Banks's supporters usually
advised, as Cavendish did here, moderation. Banks's opponents
would either become moderate or by their violence turn the Society
away from them and into Banks's camp; they were, that is, to be
offered the rope to hang themselves. Some of them accepted.

-"Blagden to Banks. 24 December 178.V

"Sir Joseph Banks to Charles Blagden. 26 December 1783,
Blagden Letters, Royal Society, B.25.

252

Cavendish

In anticipation of a crucial vote to come,
some members of the Society were busy
canvassing against Banks. On Saturday Blagden,
who was canvassing for Banks, reported to Banks
his findings to date. He named several persons who
would definitely support Banks, but some of them
would oppose any motion that would limit debate,
which meant they would oppose Cavendish's
resolution. Their compromise proposal would grant
the Society both its usual hour for the reading of
scientific papers and conducting other normal
business and also time for unlimited free debate.
Every member would have the right to make a
motion and the president would have to remain in
his chair for as long after the hour as the debate
went on. Blagden thought that the great majority of
the Society wanted Banks to remain president, but
on the question of free debate he did not know
how the Society would come down. 24

In his Saturday letter and in another letter
on Sunday, Blagden alerted Banks to the serious
trouble he was in. "Great opposition is making
against you," Blagden said, and he named some
members who were "decidedly against [Banks]
even on the subject of the Presidency." So far as he
could learn, Blagden said, they intended to put
Lord Mahon in Banks's place. The alleged
injustice done to Mutton as foreign secretary was
only the occasion of the dissensions; their real cause
was a "grudge of" very long standing," backed by
many grievances. 25 For example, Banks's opponents
charged him with excluding deserving men from
the Society because they were not of sufficient
social rank. The able mathematician Henry Clark,
they said, was kept out because he was merely a
schoolmaster. And the membership of the last
council they held in derision. The battle line, as
they drew it, was between Banks's fancy gentlemen,
or "Maccaronis," and the "men of Science."-'''

W hen Banks came to town on Monday, he
held a meeting at his house. C Cavendish, who
already had stayed away from one earlier meeting
at Banks's, may have stayed away from this one,
too. But whether or not he was there, he entered
centrally into the planning done there. To a letter
to Banks, Blagden attached a postscript dated
Monday, 29 December, which read:

Resolved. That this Society approve of Sir Jos:
Banks as their President, and mean to support him
in that office.

"Such, my dear friend," Blagden wrote to Banks,
"is the resolution Mr. C. has just approved at my
house." In Blagden 's view, the vote on this
resolution would sort out Banks's friends from his
foes. Cavendish, he added, still thought that the
resolution he first proposed would prove necessary,
since the Society would not agree that under the
present statutes they are forbidden to debate-
except at the day of elections. 27

The next day Blagden wrote to Banks that
I lorsley was busy telling his friends that Banks was
going to try to expel him at the next meeting, in
that way insuring an ample turnout of Horsley's
friends. 28 To ensure that his own friends turned out,
Banks sent a card to all members of the Society
requesting their attendance at the next meeting.
When the meeting took place, on 8 January 1784,
some 170 members came, fewer than half of whom
attended regularly. From the president's chair, facing
the massed assembly. Banks watched as "each side-
took their station and looked as important as if
matters of the utmost consequence to the State were
the subject of their deliberation."-"' As planned, the
accountant general of the Society T. Anguish rose
to make the motion. The previous two meetings of
the Society, he reminded his audience, had been

-'••Charles Blagden to Sir Joseph Hanks. 27 December 17X3;
original letter in Fitzwilliam Museum Library; copy in BM(NH),
DTC 3:180-81.

-"Blagden to Banks. 23 and 27 December 1783. Supplement to
Friend to Dr. Hutton, An Appeal to the Fellows of the Royal Society,
Concerning the Measures Taken by Sir Joseph Hanks. Their President, to
Compel Dr. Hutton to Resign the Office of Secretary to the Society for Their
Correspondence (London, 17X41, 1 1,15. Charles Stanhope, Lord Mahon.
the gifted electrician and inventor, at the close of the meeting of the
Royal Society on X January, discussed below, moved that in the future
no motion should be made in the ordinary course of business without
giving notice two weeks in advance. This motion, which was
supposed to discourage spontaneous agitation at the meetings, was
seconded and passed unanimously. Lord Mahon, who was also active
in parliament at the time of the dissensions, would go on to become
one of the founders of the Rev olution Society in 17XX. For a time he
was in harmony with the whig opposition led by Fox. Later he
became increasingly isolated, and reviled, because of his persistent
championing of the ideals of the French Revolution. F. M. Beatty.
"The Scientific Work of the Third Earl Stanhope," Notes and Records
of the Royal Society 1 1 (1955): 217-19.

26 Blagden to Banks. 27 December 17X3. Charles Blagden to Sir
Joseph Banks, 2X December 17X3, Fitzwilliam Museum Library,
Perceval II 202.

-'Postscript dated 29 December 17X3, Blagden to Banks, 2X
I )ecember 1 7X3.

-'"Charles Blagden to Sir Joseph Banks. 30 December 17X3,
Fitzwilliam Museum Library. Perceval I I 203.

-''Notes of the meeting taken by Banks, quoted in I lector
Charles Cameron. Sir Joseph Hanks. A li.. R R. S.: The Autocrat of the
Philosophers (London: Batehworth, 19.52). 134.

CopynghteO material

Politics

disrupted by debates, and at the second of these,
Horsley had threatened to keep the Society
debating the rest of the winter, the obvious intent
of which was to unseat Banks. The motion
Anguish put to the members was the resolution
approving of Banks, which Cavendish had earlier
approved. Cavendish now seconded the resolution
before the Society. Cavendish said nothing in support
of it, and there is no evidence that he said anything
else during this long night of angry speeches.- 50

The first speech was made by E. Poore, a
barrister at law in Lincoln's Inn, who called the
motion a dishonorable attempt to evade scrutiny of
Banks's conduct by praising it. The attempt would
not succeed, he said; it would not stop debate (and
did not, as Cavendish and 1 lebcrden had predicted).
Francis Maseres, cursitor baron of the exchequer,
said that for the Society to exercise its power of
election of president and council, the Society had
first to discuss the question of Banks's "abuse of
power." Horsley said that the "abuses are enor-
mous," and he went on about them at such length
that Banks's supporters clamored for the question,
almost drowning him out with their cries and with
a clattering of sticks. As a last resort, Horsley said,
"the scientific part of the Society" would secede,
which would leave Banks leading his "feeble
amateurs''' his mace standing for the "ghost of that
Society in which philosophy once reigned and
Newton presided as her minister." Maskelyne said
that if it proved necessary to secede, the "best
Society would be the Royal Society in fact, though
not in name." The mathematician James Glenie
was interrupted before he could finish what he had
to say, which was that the present council was
incapable of understanding mathematics, mechan-
ics, astronomy, optics, and chemistry, and that the
Society as led by Banks, a natural historian, was
degenerating into a "cabinet of trifling curiosities,"
a "virtuoso's closet decorated with plants and
shells." When late in the evening the motion was
finally put to a vote, it carried 1 19 to 42. By a three
to one margin, the Society wished Banks to
continue as their president.' 1 This, then, was the
outcome of the meetings, letters, maneuverings,
and canvassing. The safest course had been taken
by Banks's supporters. The resolution contained no
detail; it said nothing about limiting debates,
nothing about abuses, nothing about reforms,
nothing, that is, that might divide the majority.

253

The opponents of Banks as well as his
supporters claimed that they longed for a return of
"tranquility, order, harmony, and accord" and the
"instructive business of these weekly meetings, the
reading of the learned papers presented to the Society." i2
For three consecutive meetings, however, the
debates had prevented the reading of all new
scientific papers. Only John Michell's great paper on
the distance and other measures of the fixed stars,
which Cavendish had communicated to the Royal
Society, continued to be read at two of these
meetings, on 1 1 and 18 December, while at the third
meeting, on 8 January, no papers at all were read. 33

The main new paper read together with
Michell's at the next, the January 15, meeting was no
run-of-the-mill paper. It was a paper by Cavendish,
destined to be his most famous, "Experiments on
Air," containing his discovery of the production of
water from the explosion of gases. Coming after
three meetings in which the members had listened to
speeches contrasting the present, feeble state of the
Royal Society with what it had been in Newton's day,
and coming one week after Cavendish had seconded
the successful motion approving of Banks's presi-
dency, the reading of Cavendish's work at the first
opportunity was clearly a power move, and if by any
chance it was not calculated, the effect was the same. M

"•[Paul Maty), An Authentii Narrative of the Dissensions and Debates
in the Ro\eil Society, Containing the Speeches at Ijnyt of Dr. Horsley, Dr.
Maskelyne, Mr. Maseres. Mr. Poore, Mr. Clenie, Mr. Watson, ana 1 Mr. Maty
(London. 1784), 24-25. Supplement to the Appeal to the Fellows of the
Royal Society ; Beinn Letters taken from the Public Advertiser and Morning
Post (London, 1784). 9.

Narrative. 26-77. Supplement. 9. Royal Society. JB 31 (1782-85):
270-71. Despite charges to the contrary, in the Royal Society at this
time, the physical sciences looked to be nourishing and appreciated.
At the St. Andrew's Day meeting for elections on 1 December 1783.
Banks gave a discourse on two Copley Medals, one awarded to John
( iiiudru ke tin his paper on the variation i >! the stai VJgol, the other to
Thomas Hutchins for his experiments, which Cavendish took part in,
on freezing mercury. Kntry for 1 December I 783. Royal Society. JB.

^Narrative. 30, 70.

"Blagden to Claude Louis Berthollet. 13 January 1784. draft,
Blagden Letterbook. Vale. Royal Society. JB 31:265, 268-71. On 27
November 1783, the reading began of the paper by John Michell,
"On the Means of Discovering the Distance. Magnitude, etc. of the
I-'ixcd Stars, in Consequence of the Diminution of the Velocity of
Their Light, in Case Such a Diminution Should Be Pound to Take-
Place in Any of 'Them, and Such Other Data Should Be Procured
from Observations, as Would Be parthcr Necessary for that
Purpose," PT74 (1784): 35-57.

"Henry Cavendish, "Experiments on Air," /'7'74 (1784): 1 19-69:
reprinted in The Scientific Papers of the Honourable Henn Cavendish,
F. R. .V.. vol. 2: Chemical and Dynamical. K. Thorpe, ed. (Cambridge:
Cambridge University Press. 1°21). 161-81. The juxtaposition is
reflected in a letter Banks received from abroad at the time. Its author
begins by saying that the Royal Society's dissensions "have made
a good deal of noise on the Continent,'' that the opposition

254

Cavendish

This business-as-usual, the quiet reading of
the papers, was not to last. The new statute
requiring all motions to be announced in advance
did not produce the desired calm. Duly announced
was a motion to reinstate Hutton in his office, and
it and motions to restrain Banks's interference with
elections led predictably to renewed debates in
late January and February. 35 At a meeting in
March, Maty gave a speech and then went on to
read papers, as was his duty. Horsley was at that
meeting but few of his supporters came. Banks
took hope, w riting to Blagden that there was now
peace at the Society and that it was likely to
remain. 36 This was not to be.

The printing of the Philosophical Transactions
had been held up because of the dissensions, and
in general the affairs of the Society remained in
turmoil." Maty, who had "distinguished himself by
his violence against Sir Jos. Banks," in Blagden's
words, resigned as secretary of the Society. 38 Banks
sent another card to all members of the Society on
29 March, this one to tell them of the vacancy left by
Maty and that, "at his desire," Blagden had declared
himself a candidate for the office and that Blagden
would make an admirable secretary. Banks's
opponents took fresh offense and referred to Banks's
card as the "President's Conge d'Elire." 39

The row over the election of Maty 's replace-
ment alarmed Cavendish. New contingency plans
were laid w ith Cavendish again taking part and for
the same reason. On Monday, 5 April, Blagden told
Banks that Cavendish and his friend Alexander
Dalrymple had accompanied him home that
evening to determine the "proper measures for
preventing a few turbulent individuals from con-
tinuing to interrupt the peace of the R. S." Caven-
dish was willing to join a committee or to call a
meeting to form a plan of action and draft
appropriate resolutions. The general idea was that
the committee would present the resolutions to the
much larger meeting of members, the composition
of which was to be decided by the committee. If
the resolutions were acceptable to these members,
they would be expected to vote for them at such
times when the dissensions again interrupted the
scientific work of the Society. From a list of
members, Cavendish selected seven who would
draft the resolutions. Heberden was one of them,
and when Blagden said that Heberden probably
would not join them. Cavendish offered to go to

Heberden the next morning to try' to persuade him.
Cavendish had nothing against taking the lead
except for his general "unfitness for active
exertions." 411 That evening Cavendish wrote to
Blagden: "It is determined that Mr Aubert ck I
shall go to Dr H[eberden] & see what we can do. If
it is to no purpose a larger meeting will be called &
very likely some resolution similar to what you
mentioned proposed to them." 41

Despite his general disclaimer. Cavendish
took an "active part," Blagden wrote to tell Banks
the next day, to "render the R. S. more peaceable."
Cavendish had called not only on Heberden but
also on Francis Wollaston and Alexander Aubert,
and he was going to write to William Watson, all of
whom were on Cavendish's list of seven, and he
had even called for the meeting to take place in his
house and had settled on a time for it 42

That is the last we hear of Cavendish's
efforts to restore peace to the Royal Society. One
month later the Society voted for the secretary to
replace Maty. Hutton, the deposed foreign
secretary and still the primary rallying cause for
Banks's opponents, ran against Banks's man,
Blagden. The vote was again not close, 139 to 39,
in favor of Blagden. Banks in effect had made the
election of the secretary a vote of confidence in
him, since he had endorsed Blagden who had
served throughout the stormy times as Banks's
proxy. 45 Banks's victory was conclusive. Blagden
wrote to a foreign correspondent that the
disaffected members of the Society had not only

id Hanks seems tci have acted with "extraordinary animosity," and that
Banks's report that the troubles are "nearly quelled" is welcomed
news. The author's next observation is that Cavendish's discovery of
the production of water from air is "one of the greatest steps that have-
been made" towards understanding the elements. T. A. Mann to
Hanks, 4 June 1784, published in Henry Ellis, ed.. Original Leilas of
Eminent Literary Men of the Sixteenth. Seventeenth, and Eighteenth Centuries
(London. 184.?), 426-29, on 426-27.

Weld. History 2:162-64. Narrative, 79-134.

^Sir Joseph Banks to Charles Blagden, 6 March 1784. Blagden
Letters. Royal Society, B.26.

"Charles Blagden to le comte de C. 2 April 1784. draft,
Blagden Letterbook, Vale.

'"Charles Madden to le comte de C„ 14 May 1784, draft,
Blagden Letterbook. Vale.

' 'Weld, History 2:16.S. Supplement. 12.

'"Charles Blagden to Sir Joseph Banks, 5 April 1784. BM(NH)
DTC 3:20-21.

41 1 lenry Cavendish to Charles Blagden, Monday evening [5 April
1784,] Blagden Papers. Royal Society, c 26.

42 BlaKden to Banks, S April 1784. Charles Blagden to Sir Joseph
Banks,6Apnl 1784. BM(MI). DTC 3:22-23.

■"Weld. History 2:165-66.

Politics

>55

failed in their plan to unseat Banks but in the end
had planted him in his seat more firmly than ever. 44
After the event, the dissensions seemed hardly
more than a tempest in a teapot to Blagden, who
was surprised that foreigners took such interest in
that "foolish & trifling affair, as it really was with
us." 45 The most important evidence for this was
that science had not stopped: to a friend, Blagden
wrote that "notwithstanding the interruption given
to our business in the Royal Society by some
turbulent members . . . several valuable papers
have been read, and some discoveries of the first
magnitude announced," adding that "of these, the
most remarkable was made by Mr Cavendish." 46

During the dissensions, Cavendish was not on the
council of the Royal Society, so he had no direct
part in the Hutton affair, which had brought them
on. (If he had been on the council, the case against
Banks would have been substantially weakened.
Banks would not be exposed this way again. Before
Banks became president of the Royal Society in
1778, Cavendish had frequently sat on the council,
but in the years following, 1778-84, he was on it
only once. In 1785, the year after the dissensions.
Cavendish was elected to the council, as he was
every year after that through 1809, just before his
death.) As an ordinary member without office.
Cavendish attended all of the meetings of the
Society at which the great debates took place.
Insofar as we have record, he made no public
speeches at any of them. He seconded, undoubtedly
by prearrangement, the motion approving Banks's
presidency, but nothing more. That was all that
was needed, for Cavendish was not simply another
member of the Society. First of all, he was a
Cavendish, a name which carried an authority of its
own. He owed nothing to, and needed nothing
from. Banks, and for him to act out of personal gain
or personal loyalty or disloyalty would have been
seen as acting out of character. Second, he was
universally respected for his achievements in
physical science, not natural history, and he was
also known to be a good mathematician. If
Cavendish had sided with Horsley and his friends,
mathematicians who styled themselves as the
genuine scientific element of the Society, Banks's
credibility would have been shaken and the voting
conceivably could have gone differently. Blagden
fully understood this, which is why Cavendish was

the key to his stratagems to save Banks's presidency,
as his letters to Banks reveal. Cavendish's endorse-
ment of Banks by seconding the crucial motion was
a scientific answer to Horsley's characterization of
Banks's men as feeble amateurs.

Blagden, in a letter of 2 April 1784 in which
he referred to the dissensions at the Royal Society,
also spoke of "our internal operations in politics, &
the consequent general election, [which] have set
the whole kingdom in a ferment; it is a very
interesting scene which the wisest & steadiest
among us contemplate not without emotion." 47
Scientific and general politics were constantly
being compared in the course of the dissensions.
The one side spoke of the "ruins of liberty," the
other side of Englishmen "apt to be mad with
ideas of liberty, ill understood." 48 Again, the one
side spoke of the "leveling spirit and impatience of
all government which infects the present age," the
other side of the Royal Society as a "republic,"
according to which all laws decided by the council
are to be debated by the entire membership
whenever a mover and a seconder wish it. 4 '' Or

"Blagden to Ic comtc dc C 2 April 17X4.

"Charles Blagden to Sir Joseph Banks, 9 August 1788, BL Add
Mss 33272. pp. 50-51. Blagden believed that the affair was behind
them. While it is true that the dissensions did not flare up again,
smoldering resentments continued to the end of Banks's long
presidency, in 1820. David Philip Miller. "Sir Joseph Banks: An
Historiographical Perspective," History of Science 19 (1981): 284-92.
on 289. Some dozen years after his dismissal as foreign secretary,
Charles Mutton gave an embittered description of the Royal Society
in his Mathematical and Philosophical Dictionary. The entry "Royal
Society of London" begins: " This once illustrious body . . ." The
meeting hour of the Society had been adjusted to the convenience of
"gentlemen of fashion." The Philosophical transactions "were, till
lately, very respectable. . . . Indeed this once vers respectable-
society, now consisting of a great proportion of honorary members,
who do not usually communicate papers; and many scientific
members being discouraged from making their usual
communications, by what is deemed the arbitrary government of the
society, the Philosophical Transactions have badly deteriorated."
Charles Hutton. A Mathematical and Philosophical Dictionary. 2 vols.
(London. 1795-96) 2:399-400.

4 "Charles Blagden to Charles Grey, 3 June 1784. draft. Blagden
I <etterbook, Yale .

"Blagden to le comte de C, 2 April 1784. Writing to Banks
three days later, on ,S April, about the dissensions, Blagden added a
postscript concerning the elections in London.

J "J. (denies speech on 8 January, quoted in Narrative, 70.
Blagden to Berthollet, 13 January 1784.

4 ''Blagden to Banks. 28 December 1783. Letter written by
Michael Lort to Lord Percy. 14 February 1784. at the height of the
dissensions, quoted in Weld, History 2:169. Lort was a friend of
Cavendish, who brought him as a guest to the Royal Society before
he was elected. Lort elaborated his v iew of the connection between
the politics of the Royal Society and that of the country: at the Royal
Society "every fortnight a set of orators get up and fatigue
themselves, and much the greater part of the Society w ith virulent

256

Cavendish

again the one side urged a democratic solution to
the abuses of the Society, while the other warned
of an illegal "democratic infringement on the
principles of the constitution," which was "very
much like what w as passing in another place." 50 The
analogy between scientific debates and those
"passing in another place," parliament, was made
explicit. W hen speakers against Banks were shouted
dow n and the question w as demanded, Maskelyne
said that he had been at other meetings that
modeled their debates after the example of
parliament, and there the question was not put
until everyone had had a chance to speak. 51 The
favorite analogy was between Banks as president of
the Royal Society and the king or some official in
government. Horsley described Banks's call upon
the members to elect Blagden as their secretary as
a "nomination by the president, as their sovereign, of
the person he would have them chuse; which is
exactly similar to the proceeding of the king in the
nomination of a new bishop." 5 - Horsley's colleague
Maty said that his view of the presidency of the
Royal Society is of a "presidency of bare order, like-
that of the Speaker of the House of Commons, and
in Council the President ought not to lead more
than any other person." 5 ' Banks's opponents talked
of his despotism, of his dictatorial ways, of his wish
for dominion. The age of absolute monarchs was
over, but Banks seemed not to have noticed, they
said. But the supporters of Banks did not wish for
an absolute monarch any more than his detractors
did, and none was more definite on this subject
than Henry Cavendish.

In explaining Cavendish's behavior to
Banks, Blagden drew the appropriate parallel
between Cavendish's position in science and that
of his relatives in politics. "The sum is," Blagden
wrote to Banks, "that like his namesakes
elsewhere, he is so far loyal as to prefer you to any
other King, but chooses to load the crown with
such shackles, that it shall scarcely be worth a
gentleman's wearing." 54 With regard to Cavendish's
"grievance" against Banks, Blagden w rote again to
Banks, "It is exactly the old story of an absolute
Monarchy, whereas he [Cavendish] thinks the
Sovereign cannot be too much limited." 55 In a
more reassuring voice, Blagden wrote to Banks
after a meeting with Cavendish, "The utmost
consequence will be, some diminution of power,
but none of dignity." 5 ' 1

I'/ie Nation

Although the arena in which Henry
Cavendish acted upon his political views was the
Royal Society, in his manner of acting he
resembled the Cavendishes in parliament. An
appropriate Cavendish to bring up for comparison
is William Cavendish, the fourth duke and older
first cousin to Henry. The fourth duke held high
positions in government including, briefly, de-
position of prime minister in 1756-57. In the
political diary he kept, the fourth duke revealed,
his editors write, his "complete self-assurance as to
his place in the order of the world. He sits in
[Privy] Council as naturally as at his dining-room
table. Devonshire's assumption was that Creat
Britain should be governed by an aristocracy, with
himself a principal. . . . [His] main concern was
always to preserve harmony amongst His Majesty's
serv ants." The fourth duke had no intimate friends
in political life. "This detachment was natural to
him and inevitably confirmed his exalted station.
Here however lay the key to Devonshire's
usefulness, recognized by everyone, lie was the
supremely objective man, never led away bv
passion, completely reliable and so the ideal
receiver of confidences." Devoted to work and

and illiberal charges against the President. Horsley, Maskelyne.
Mats. Maseres, and Poorc are the leaders of this hand, who are
joined by all those turbulent spirits that are impatient of all
government and subordination, which is indeed the ^rcat evil and
disease of the times. I believe 1 have prolonged and inereased my
complaints by going out twice to vote against these innovators, who
kept the society talking and disputing and balloting till near eleven
and twelve o'clock, though they have been baffled in almost every
question by near three to one. I w ill say nothing of our politics; our
newspapers contain scarce anything else." Michael l.ort to Bishop
Percy. 24 February 1 7S4. published in Literary Anecdotes of the
Eighteenth Century, 9 vols.. John Nichols, ed. (London. 1812-16) 7:461.

"■"The accountant general Anguish's speech on 12 February,
quoted in Narrative, 1 12.

s, Maskelyne's speech on 8 January, quoted in Narrative, 62. The
Royal Society and parliament occasionally came together in the same
person. C. J. Phipps, Lord Mulgrave. for example, w as active both in
the debates of the House of Commons and in those of the Roval
Society. When Blagden came to see him on the subject of the
dissensions. Lord Mulgrave talked to him as much as "his present
political agitation would allow." Lord Mulgrave strongly urged Hanks
and his supporters against temporizing, since discontented men were
"never made quiet by coaxing." Blagden, who used the analogs
himself, thought that Lord Mulgrave carried the analogs of "11
|ouse| of C [ommons] ideas to our Society" farther than w as justified.
Blagden to Banks. 23 December 1783.

,J Horsley's speech on 1 April, quoted in Supplement, 12.

"Maty's speech on 12 February, quoted in Narrative. 99.

"Blagden to Banks. 22 December 178.V

"Blagden to Banks, morning, 24 December 1783.

" Blagden to Banks, 24 December 1783.

Politics

257

duty, everything the fourth duke did he did well. 57
These eharaeteristics of the fourth duke — self-
assured, conscientious, cautious, withdrawn, com-
petent, and supremely objective — were those, by
and large, of the Cavendish family and, in parti-
cular, of that member who distanced himself
farthest from the active political life of the nation,
Henry Cavendish. 58

Like the fourth duke and like other
politicians of his family, Henry Cavendish
preferred to work in committees, to exercise power
behind the scenes rather than to come forward as a
leader. That behavior agreed with his under-
standing that power should be exercised by
councils of serious men of independent judgment.
He did not want to be president of the Royal
Society, nor did he want to make or depose
presidents, but he was always ready to advise
presidents and others, as a call of duty, and always
in the interest of stability and harmony.

Like his namesakes in government, whatever
Henry Cavendish did, he did well. Whatever he-
did not do well — which included delivering
speeches, inspiring men to follow him into political
battle, his special "unfitness" — he did not do at all.
He acted constantly in society, only his was not the
given society of high fashion and politics, his
birthright, but that of his own choosing, the society
of scientific men. He acted from his strengths,
which were his intelligence, his sense of fairness,
his impartiality, and his ability to work with groups
of equals to arrive at decisions for common action.
His strengths also included, as his participation in
the events of 1783-84 show, an understanding of
political behavior; he was a close observer of men
just as he was of natural phenomena.

In drawing comparisons between Henry
Cavendish's political views and those of his
namesakes, Blagden knew his subject well. He was
a frequent caller at Devonshire House, where the
Cavendishes came together with Fox and like-
minded whigs to talk about politics, and, of course,
he was an intimate of Henry Cavendish, whose
views on politics were a private matter. And
Blagden was well informed on and greatly-
interested in national politics.

In his capacity as secretary to the Royal
Society Blagden wrote to correspondents in 1789 to
say that there was no science to report, that
"everybody's attention seems turned to politics." 59

The next year he wrote that science throughout
Europe was languishing and that the Royal Society
had heard nothing important since William
Herschel's paper on the rotation of Saturn's ring,
"the minds of men being turned to greater
interests."'' 11 Two years later Blagden on a visit to
France was mobbed and nearly hanged. Banks
wrote to him that in England their "minds are
much heated" by the dreadful state of France and
that he trusted that the English people would learn
a lesson from it.'' 1

It seemed to Blagden that Cavendish too
was caught up in the current distractions and
malaise. He wrote to Richard Kirwan in 1790 that
"Mr Cavendish does not seem to be very busy."''-'
From someone, perhaps Blagden, Kirwan had
heard that "Mr. Cavendish talks politics." He was
surprised because Cavendish had been silent
during "Ld North's Rump Parliament, in wh his
family were so much engaged. "'' , Then came the
wars with France, and at the George & Vulture,
Cavendish was "freer than usual," saying that
"minister & measures" had to be changed and that
they "should have confidence in Fox."'' 4 Henry
Cavendish stood by his family in politics, by the
brilliant and flawed Charles Fox, whose public
address was, in effect, Devonshire House in
London. Present during a conversation about war
the sooner the better. Cavendish "said he could
scarcely refrain from bursting out."' 6 Blagden
recorded a good many of Cavendish's observations

S7 The Devonshire Diary: William Cavendish, Fourth Ihike of
Devonshire, Memoranda mi Stair of Affairs, 1750-1762. ed. P. D. Brown
and K. W. Schwcizcr, Camden Fourth Scries, vol. 27 (London: Royal
Historical Society. 1982) 27: 19-21.

^Caution has been singled out by other writers on Henry
Cavendish as a characteristic common to him and to the Cavendishes
in general. The family motto Cavendo tutus, a play on words meaning
"Safe by being cautious," was Cavendish's guide throughout his life
according to his main biographer George Wilson. The Life of the
Honourable llenn Cavendish (London. 1 SS 1 ), 190.

"Charles Blagden to William Farr, 24 Jan. 1789, draft, Blagden
Lcttcrbook. Royal Society. 7:206. Charles Blagden to M. A. Pictet, 9
Apr. 17X9. draft, ibid.. 7:223.

'■"Charles Blagden to William Farr. 31 July 1790, draft, Blagden
Lcttcrbook. Royal Society, 7:429.

'■'Charles Blagden to Sir Joseph Banks, .S Sep. 1792. BL Add
Mss 33272. pp. 107-H. Sir Joseph Banks to Charles Blagden. 19 Feb.
1793, Blagden Letters, Roval Society. B.41.

'•-Charles Blagden to Richard Kirwan, 2(1 Mar. 1790, draft,
Blagden Lcttcrbook. Royal Society, 7:322.

"Richard Kirwan to Sir Joseph Banks. 10 Jan. I7K9. copy.
BM(NH), D'I'C, 6:122-24.

"16 Mar. 1795. Blagden Diary, Royal Society. 3:back p. 50.

»20 Dec. 179.5, Blagden Diary. Royal Society, 3:back p. 82.

258

Cavendish

about the ongoing wars, though in each instance
the note is so brief that only the tenor of
Cavendish's opinion can be got. But that is
sufficient for us to get an j c | ca of Cavendish's view
of nations in conflict, France, Prussia, Russia,
Austria, and Britain. The conversations took place
at the George cV Vulture and the Crown & Anchor
and Banks's house. Blagden, a great admirer of
Napoleon, would set out theses of Realpolitik. He
presented Cavendish with the arguments for
setting on Prussia while holding out peace. "Never
was a nation so mad," Cavendish responded.'''' The
only possibility of a combined resistance to the
French was by a "fair intelligence" between
Prussia and Austria, Cavendish said, to which
Blagden replied "impossible," since Austria's goal
was to swallow up Prussia.'' 7 On the report of a new-
war with America, Cavendish said that the
Americans were "now more moderate than their
predecessors." Blagden rejected that opinion on
the grounds that Americans would hold onto their
places at any cost, to which Cavendish "assented &
looked in agitation." Blagden said that England
had best turn into a nest of pirates and war against
all the world, and that England was likely to be at
war soon with Russia: "to all this /Cavendish/ sadlv
assented."'' 8 On two major points Cavendish and
Blagden agreed. In the making of a new ministry,

in which Cavendish's "family took an active part,"
Blagden said he was for the old opposition, Fox. To
Blagden's remark that all of mankind had gone
mad together, Cavendish "thought there was a
great diminution of common sense in the world. " 69
Taken together these and other comments by
Cavendish point to a man who looked to reason in
human affairs and who was dejected because he
did not find much there.

If one looks at the dissensions of the Royal
Society as a kind of experiment of the Enlighten-
ment, a test in real life of its characterizing beliefs,
the outcome is subject to interpretation. But it
seems clear that through it all. Cavendish acted
consistently upon certain of these beliefs. He
trusted that disputes can and ought to be settled by
discussion between men who are fair, moderate,
informed, and willing to exercise their reason. In
the eighteenth century, as in any other, anyone
who held that expectation of human nature was set
up for disillusionment.

""Ibid.

"30 Nov. 1*04. Blagden Diary, Royal Society, 4:286.

' M S May 1806, Blagden Diary, Royal Society, 4:442.

m i Apr. 1804, Blagden Diary, Royal Society. 4:217. This
exchange on the unreason of people may not have had to do with
politics, but it would apply.

CHAPTER 3

C^ir and Water

Good Air

"Chemistry is the rage in London at
present," John Playfair noted in his journal on a
visit in 1782.' This observation sets the stage for
the next researches of Henry Cavendish.

In our account of Cavendish's earliest work,
we discussed the role of phlogiston in chemistry.
The period was the 1760s, a relatively confident
time for the followers of phlogiston. In the period
we now take up, the 1780s, phlogiston was ques-
tioned, and before the end of the century chemists
will have renounced it. The opponents of phlo-
giston were called "anti-phlogistonists," and because
phlogiston is absent from the chemistry we learn
today, we are all anti-phlogistonists; and for that
reason, we may have difficulty following the argu-
ments of the early chemists. In this chapter we will
be concerned primarily with the chemistry of the
components of common air, "dephlogisticated air"
(our oxygen) and "phlogisticated air" (our nitrogen
mainly), and with two other distinct gases, "nitrous
air" (nitric oxide) and "inflammable air" (hydrogen).
The meanings, though not the chemistry, of
"dephlogisticated" and "phlogisticated" air were
possibly straightforward, referring to the absence
and presence of phlogiston.

Upon combining different kinds of air,
chemists observed a large change in volume, the
basic understanding of which did not come until the
very end of Cavendish's life, long after the end of his
work in chemistry. To look ahead: in 1808 Joseph
Louis Gay-Lussac reported that gases combine in
simple proportions and that their contraction upon
combining bears a simple proportion to their
original volume; in 1811 this law of combining
volumes received a molecular interpretation by
Amadeo Avogadro. In Cavendish's period, the
major accomplishment of chemistry was the
distinction between various kinds of airs, the first
step in the chemistry of the gaseous state of matter.
That came about through the chemistry of phlogiston

and through the invention of subtle techniques in
the laboratory. Unless one takes the ahistorical
position that all once good science becomes
wrongheaded once it is superseded, phlogiston
chemistry' was good chemistry up to a point.

Cavendish's second publication in chemistry
came in 1783, seventeen years after his first, in
1766; both were about air. Having occupied him-
self in the meantime with researches on electricity
and tasks for the Royal Society, in 1 778 he began a
new series of researches that would continue for
eight years. The stimulus was a new instrument for
studying air, the eudiometer.

The eudiometer incorporated a fundamental
process, the "phlogistication" of air, which was
itself a central problem of chemistry, so that the
eudiometer was at the same time an instrument of
meteorology, an instrument for the study of gases,
and a physical process that needed clarification. Its
inventor was Joseph Priestley.

Priestley, a dissenting minister in Birming-
ham, was approximately the same age as Cavendish
and had scientific interests parallel to those of Cav-
endish. Priestley had preceded Cavendish in elec-
tricity; as we have noted, his book on electricity in
1767 had been a stimulus to Cavendish's researches.
In pneumatic chemistry, the order was reversed. In
1772, in a long paper in the Philosophical Transactions,
Priestley reviewed the territory already explored in
pneumatic chemistry and added to it a new gas,
nitrous air (nitric oxide), the first of his many new
gases. 2 Priestley was led to this discovery, he said,
by a conversation with Cavendish about experi-
ments done by Hales. 5 In technique, too, Priestley
learned from Cavendish and went beyond him;

'John Playfair, The Worts of John Playfair, ed. J. (j. Playfair, 4
vols. (Edinburgh, 1822) l:xxxv.

^Joseph Priestley, "Observations on Different Kinds of Air," PT
hZ (1772): 147-264. Priestley had already published a pamphlet on
artitleial sparkling water, made bv impregnating water with fixed air.

'Ibid., 210.

260

Cavendish

Cavendish had stored water-soluble gas over
mercury, a decisive innovation for the further
development of pneumatic chemistry, and Priestley
made the mercury trough a tool of discovery.
Priestley's work on gases in turn stimulated
Cavendish to return to the subject, at first in
connection with Priestley's new gas, nitrous air, the
agent of Priestley's new instrument.

The eudiometer is based upon a striking
property of nitrous air: "I hardly know any
experiment that is more adapted to amaze and
surpri/.e than this is," Priestley wrote, "which
exhibits a quantity of air, w hich, as it were, devours
a quantity of another kind of air half as large as
itself, and yet is so far from gaining any addition to
its bulk, that it is diminished by it." 4 Nitrous air
was another means in addition to breathing,
burning, and putrefaction of consuming "good" air.
Moreover, this new way of phlogisticating air
promised a new exactness in the study of air; the
decrease in the volume of the mixture of a
measured quantity of common air and a measured
quantity of nitrous air over water (the products of
the reaction being absorbed in the water) measured
the goodness of the common air, a better test,
Priestley said, that putting mice in it to see how they
fared. The "eudiometer," measurer of goodness,
was an addition to the tools of science and of public-
health. Bad air caused bad health. 5

In his first experiments on gases. Cavendish
had estimated the combustible portion of common
air by the loudness of the explosion w hen it was
detonated with inflammable air; he had, in effect,
invented a crude sort of eudiometer/' The new,
potentially exact instrument Cavendish described
in 1783 in the Philosophical Transactions: "Dr.
Priestley's discovery of the method of determining
the degree of phlogistication of air by means of
nitrous air, has occasioned many instruments to be
contrived . . . ." 7 The variant of the instrument that
Cavendish preferred, as did several other
eudiometrists such as Tiberius Cavallo and Jan
Ingen-Housz, was the "more accurate" eudiometer
invented by the Florentine Felice Fontana in 1775.
Fontana pursued the study of airs in Cavendish's
way by determining their specific gravities with
great exactness. With his eudiometer Fontana
tested the air in different locations in Furope and
in London, publishing two papers on the subject in
the Philosophical Transactions for 177°. With his

instrument, Fontana had come to the conclusion
that the air in different places and at different
times was almost the same and that the large
differences other observers measured arose from
errors in their methods.* Cavendish agreed, but the
agreement was by no means general among
chemists. At about the time Cavendish took up the
subject, Cavallo wrote in his treatise on air that the
laws of the differences in the purity of common air
in different parts of the world was "perhaps the
most interesting part of the study of elastic fluids.'"'

The problem was interesting to Cavendish, but the
solution lay not in the differences of samples of
common air but in their uniformity.

Fontana's eudiometer was essentially a
container for mixing nitrous and common airs. By
Cavendish's modified instrument 10 and method,
the quantities of the gases before and after mixing
were determined by weight rather than by volume.

The weighing, which Cavendish did under water,
determined the decrease in the common air, w hich
was the measure of the pure, or good, air. For this
measure, or "test" of the air, Cavendish introduced
a "standard" and a scale of measurement, which
assumed (as Cavendish had determined) that the
composition of the atmosphere is constant: the
upper fixed point of the scale was the "standard" 1,
which stood for the goodness of common air; the
low er fixed point was the "standard" 0 of perfectly
phlogisticated air (nitrogen). According to this
scale, the "standard" of any sample of air was

J Ibid.. 212.

^Tiberius Cavallo, .1 Treatise on /tie Nature and Properties of Air,
unit Other Permanently Elastic Fluids. 'Hi Which Is Prefixed, an
Introduction In Chemistry (London, 1 781 ), 45.i-.S7.

6 George Wilson said this technique might be called an
"Acoustic Eudiometer." The Life of the Honourable Henry Cavendish
(London, 1851), 41.

7 Hcnrv Cavendish, "An Account of a New Eudiometer," / J '/'73
(1783): 106-35; Set. Pap. 2:127-44. on 127.

"Felice Fontana, "Account of the Airs Kxtracted from Different
Kinds of Waters; With Thoughts on the Salubrity of the Air at
Different Places," PT 69 (1779): 432-53. Rembert Watermann.
"Eudiometric ( 1 772—1805)," Technik-Gcschichte 35 (1968): 293-319.
on 302-3.

''( '.a\ alio. A Treatise on the Salute anil Properties of Mr, 477.

'" The eudiometer Cavendish described in his paper of 1783 was
not what later became known as the "Cavendish Eudiometer,"
which the Cavendish Society adopted as its emblem in the early
nineteenth century. The so-called Cavendish eudiometer was an
electrically detonated eudiometer invented by Volta. Cavendish used
such an apparatus in his experiments on the condensation of water,
but he never referred to it as a eudiometer. W ilson. Cavendish, 42—43.
Kathleen R. Farrar, "A Note on a Eudiometer Supposed to Have
Belonged ro Henry Cavendish," Hrilish Journal for the History of
Science I (1963): 375-80.

Copy rig hi eo

Air (Did Water

261

PLATE X. Eudiometer. Figure 1 shows the main apparatus, a glass cylinder A with brass cap and a cock at the top and an open brass cap at the
bottom fitted into a socket of a bent brass holder as "a bayonet is on a musquet." The whole is submerged in a tub of water. Figure 2 is an inverted
bottle for holding air. and Figure 3 is a standard measure of air. Cavendish's method is to put a certain measure of nitrous air (nitric oxide) into the
inverted bottle and a certain measure of respirable air (oxygen) into the glass cylinder. The cylinder is then set on the socket and the bottle over
the cock, and the two kinds of air arc mixed in the bottle. Cavendish determines the quantities of air used and the diminution upon mixing the two
kinds of air by weighing the vessels containing the air under water with a balance. "An Account of a New Eudiometer,'' Philosophical
Transactions 73 (1783): 134.

proportional to the quantity of deplogisticated air
(oxygen) in it. The standard of pure dephlogisticated
air (pure oxygen) Cavendish found to be 4.8, later
adjusted to 5. It was not known then that the airs
reaeting in the eudiometer, our nitric oxide and
oxygen, combine in different proportions, the
reason for the vastly different purities of air
reported from different places. What was known,
certainly to Cavendish, was that the only way to
achieve uniform results was by laying down a
uniform procedure, and that was the burden of
Cavendish's publication." He also gave results
from sixty days of trials with the instrument, on
clear, soggy, and wet days, early in the day and late,
from which he concluded that within the error of
the measurement, there was no difference in the
degree of phlogistication of the air from place to
place and time to time. With these measurements.

which he made with the utmost accuracy (with
"superhuman care," as they have been described),
he arrived at a result which subsequent chemists
have translated into terms and quantities corre-
sponding to our understanding of the atmosphere:
the concentration of oxygen in the atmosphere is,
according to Cavendish, 20.83 percent, which is
remarkably near the currently accepted value of
20.95 percent. In making this comparison, how-
ever, Cavendish is credited with a somewhat greater
precision that he would likely have claimed. 12

11 Edward Thorpe. "Introduction." Henry Cavendish, The
Scientific Papers of the Honourable Henry Cavendish, F.R.S., 2 vols.
(( lam bridge: Cambridge University Press, 1921 > 2: IK.

'-Separated off from his "Experiments on Air" is another
manuscript of fourteen pages on eudiometer tests made in Kensington
and London (Creat Marlborough Street) and reported in Cavendish's
paper of 1 783, "Miscellaneous Data on Eudiometer Experiments,
1780-81" (not Cavendish's label). Cavendish Mss II, 8. The cxperi-

Copvr

262

Cavendish

Cavendish advocated his standard and com-
mon scale because eudiometers "differ so much,
that at present it is almost impossible to compare the
observations of one person with those of another." 13
(Like Fontana, Cavendish was unable to persuade
his fellow chemists to adopt his demanding
procedure. 14 ) In this regard. Cavendish's paper on
the eudiometer can be seen as a continuation of his
paper on the meteorological instruments of the Royal
Society and their uniform usage. Only the Royal
Society did not need to include this instrument
among the other meteorological instruments it
used for its daily record of the weather, since, as
Cavendish showed with it, there was no significant
variation in the goodness of the air to record.

At the end of his account of the eudiometer.
Cavendish compared its action with the sense of
smell. The eudiometer was not like the telescope,
an instrument that extended one of the human
senses. On the contrary, by their sense of smell
people could detect "infinitely smaller" quantities
of impure air than they could detect using the
eudiometer; for example, they could detect a ten-
ounce measure of nitrous air released into a twelve-
by-twelve-foot room, an immeasurably small
quantity that would not alter the eudiometer test
by more than 1/47,000 part. The nitrous test
showed the degree of phlogistication "and that
only," but this limitation did not diminish the
usefulness of the test in experiments; for our smell
is no "test," Cavendish said, of phlogistication, and
there are ways of phlogisticating air that do not
impart a smell to it as there are ways of imparting a
smell that do not phlogisticate. ls In the last
analysis. Cavendish's conclusion was an affirmation
of instruments of measurement in science.

At the time Cavendish published his work on the
composition of air, the atmosphere became a
medium of human transport. The balloon was
invented, and with it a new kind of man appeared
in the world, the "aronaut." Much about this
earliest human flight was empirical and derring-do,
but there was also an element of science, both in
the principles of flight and in the use of flight for
meteorology. Cavendish took an immediate
interest in both. There was born a new field of
applied pneumatic chemistry.

In fact Cavendish was regarded at the time
as a kind of founding father of balloon flight, which

went back to his first publication on air, in 1766.
From Cavendish's description of inflammable air, it
was self-ev ident to Black that balloons filled with
this lighter-than-common air were a practical possi-
bility. Black spoke about it with friends and in his
lectures, but he did not bother to do the experi-
ment."' "Theoretical flying," Blagden said, "has been
a topic of conversation among our philosophers as
long as I can remember, at least ever since Mr
Cavendish discovered the great lightness of
inflammable air." 17

In 1 7S2 the French brothers Joseph and
Ftienne de Montgolfier experimented with
balloons filled with inflammable air and with hot
air, and in the following year, they gave a public-
demonstration of a hot-air balloon. |s Soon people
began going up in balloons, fulfilling an age-old
dream. Balloons created a sensation in France and
mixed feelings in Britain. Not without a touch of
national envy, the British spoke of "Balloon
madness" or else of missed opportunity: the

merits continued utter ( Cavendish's move to I lampstead in 1 782. where
he recorded tests of air in "Register of Test Air." and "Eudiometer
Results of Air Taken by Dr. Jeffries" (not Cavendish's label), in
Cavendish Mss. Misc. and II. 9. respectively. There is another
untitled manuscript comparing his. Fontana's. and Ingcn-I lous/'s
methods, in the miscellany of his papers. A hundred years later, in
admiration. William Ramsay compared Cavendish's measurements
with the latest results. 79.04 percent nitrogen and 2<).4d percent
oxygen. Ramsay, Gases of the Atmosphere, 125-26. Cavendish's result is
even closer to the more recent value of 20.95 percent: Peter
Brimblecomhc, "Karliest Atmospheric Profile." AVi' -Scientist 76 ( 1977):
364-65. Bent Soren Jorgcnsen, however, cautions that in extolling
Cavendish's accuracy in his atmospheric determinations, modern
chemists have overlooked a remark by Cavendish in a publication a
year after his paper on the eudiometer; in this subsequent paper, in
1784, (Cavendish noted that his dephlogisticatcd air contained
impurities amounting to one thirtieth of its volume, which led him to
suspect that common air contains one fifth part dephlogisticatcd air
(that is. closer to 20 percent than to 20.83 percent). Even if
( Cav endish's v alue for the proportion of oxygen in the atmosphere may
not be quite as close to our v alue today as the histories of chemistry
maintain. Jorgcnsen says, (Cavendish was much closer than Scheele,
Lavoisier, and Priestley, whose v alues were between twenty-five and
thirty percent. "On a Text-Book Krror: The Accuracy of Cav endish's
Determination of the Oxygen Content of the Atmosphere."
Centaurus 12(1968): 132-34.

"Cavendish, "Account of a New Eudiometer," 141.

l4 Jan (iolinski. Science as Publii Culture: Chemistry and Enlightenment
in Britain, I760~182i>(( Cambridge: Cambridge I'niversiry Press. 1992), 124.

l5 Cavendish, "Account of a New Eudiometer," 144.

"'In a letter from Joseph Black to James 1 ,ind, in William Ramsay,
The Life and Letters of Joseph Black, M.I). (London: Constable. 1918), 77-78.

''Charles Blagden to le Comte de C, 2 Apr. 1783, draft, Blagden
Lettcrbook. Vale.

IS W. A. Smeaton, "Montgolfier, Etienne Jacques de; Montgolfier.
Michel Joseph de." DSB 9:492-94. The early experimentation in
Trance with balloons filled with inflammable air and hot air is discussed
in (Charles C. Gillispie, The Montgolfier Brothers and the Invention of
Aviation 1 783-1 784 (Princeton: Princeton University Press. 1983), 15-31.

Mr and Water

263

French made no scientific observations from their
balloons, Banks complained. 1 '' It was to be hoped,
Banks said, that the English would "not rise to the
absurd height we have seen in France." 20

Cavendish appreciated the French achieve-
ment in his way. 21 Since the principle of the
inflammable-air balloon was fully understood on
the basis of weight, Cavendish's interest was
directed to the hot-air balloon. Evidently to decide
if the hot air alone caused the balloon to rise or if
the balloon also depended on a substance lighter
than common air given off by the burning material.
Cavendish and Blagden collected the air from
burning straw and leather and tested it with a
eudiometer. Finding it to be a mixture of gases
heavier, not lighter, than common air, 22 they
concluded that hot-air balloons ascend solely
because of the rarefaction of air. 23 In practical
terms, the hot-air balloons were extremely
dangerous and clumsy; Blagden expected nothing
of them, but he thought that inflammable-air
balloons could bring about an "important revolu-
tion in human affairs." 24

Not immediately but before long, balloons
appeared in the sky over England too. The first
balloon to carry a person there was that of the
Italian Vincenzo Lunardi; the second that of the
Frenchman Jean Pierre Blanchard, who was joined
by the first English aeronaut, John Sheldon,
professor of anatomy at the Royal Academy; and
the third another balloon of Blanchard, who went
up more times than anyone, 25 this time accom-
panied by the American physician John Jefferies. 26
Cavendish was there to observe these multina-
tional adventures. He and his friends — Alexander
Aubert, Alexander Dalrymple, Charles Blagden,
William Herschel, Nevil Maskelyne, William
Heberden, William Roy, and Jesse Ramsden —
observed the balloons from Putney Fleath, Aubert's
observatory in Austin Friar's, and elsewhere. 27 With
theodolite and clock, they recorded the position
and time every minute or two while the balloon
was in sight. Cavendish calculated the course of
the balloon as if it were a low-flying comet. 28
Cavendish took much interest in the science of
flying, but unfortunately his manuscripts on this
subject have been lost. 29

Balloons offered their passengers "scenes of
majestic grandeur," raising them to an "unknown
degree of enthusiastic rapture and pleasure. " , " But

to Cavendish, balloons were a means of elevating
the scientific laboratory thousands of feet above
the earth. He could now extend his measurements
of the composition of the air to great heights.
Through Blagden, Cavendish asked Jefferies
to sample the air during his flight with Blanchard
on 30 November 1784. Jefferies took with him
five glass phials filled with distilled water, and
at various heights he emptied the phials and
bottled the air. With the eudiometer. Cavendish
tested these samples and compared them with air
taken on the ground at Hampstead, establishing
that there is little systematic variation in the
concentration of dcphlogisticated air (oxygen) in
the lower atmosphere. He did not publish this
finding; the credit is given to Cay-Lussac for his
research twenty years later.' 1 We note that

' 'Joseph Banks to Charles Blagden. 22 Sep. and 12 Oct. 1783,
Blagden Letters, Royal Society, B.29-30.

2°Sir Joseph Banks to Charles Blagden, 22 Sep. 1784. Blagden
Letters, Royal Society, B.29.

21 In Cavendish's papers is a testimonial signed by Benjamin
Franklin among others of a Montgolfier experiment on 21 July 1783
and also an extraet. in Blagden's hand, about Montgolfier from the
Journal E.niyclopedii/ue.

"Notations in both Blagden's and Cavendish's hand, beginning
"Smoke of Straw," Cav endish Mss. Mist .

-''Letter from Charles Blagden 5 Dee. 1783, draft, Blagden
Letterbook, Vale.

Z'Charles Blagden to Claude Louis Berthollet. 19 Dee. 1783,
draft, Blagden Letterbook, Vale.

-'Blanchard went up in balloons in many places, such as in
Philadelphia in an inflammable-air balloon, in which he made
medical observations, Jean Pierre Blanchard. Journal of My Forty-
Fifth Ascension (Philadelphia. 1793).

-'•Charles Mutton, "Aerology," in Mathematical and Philosophical
Dictionary, vol. 1 (London, 1795). 38-40.

"Charles Blagden to Sir Joseph Banks, 17 and 24 Oct. 1784.
copy. Banks Correspondence, BM(NH). DTC. 4:75-78.

-"Alexander Aubert to William Herschel. 13 Sep. 1784. Royal
Astronomical Society, Herschel M 1/13. Charles Blagden to Sir
Joseph Banks. 16 Sep., 1784, Banks Correspondence, Kew, 1:173.
"Path of Balloon," for an ascent on 16 Oct. 1784. Cavendish Mss
VIII, 24. In Cavendish's hand. "Result of Observations of Balloons,"
Blagden Collection. Royal Society. Misc. Notes. Archibald and Nan
L. Clow, The Chemical Revolution: A Contribution to Social 'Technology
(London: Batchworth Press, 1952), 156.

2 ''For his sketch of Cavendish in 1845, Lord Brougham
borrowed two manuscripts that are now lost: " Theory of Kites" and
"On Flying." Their existence and loan to Brougham are noted in
Cavendish's manuscripts at Chatsworth.

"' Thomas Baldwin. Aeropaidia: Containing the Sanative of a
Balloon Excursion from Chester, the Eighth of September, 17X5 (London.
1785), 2.

'"Kudiometer Results of Air Taken by Dr. Jefferies." and "Test
of Air from Blanchard's Balloon." Cavendish Mss II. 9 and 10.
Thorpe, in Cavendish. Sri. Pap. 2:22. Jefferies' air samples were
numbered, but the explanation of the numbers is not in Cavendish's
Mss, and it was believed lost. However, recently it was located in
Jefferies' account of his flight, from which the earliest atmospheric
profile, the "Cavendish-Jcfferies profile," has been reconstructed,
showing that at the various sampling elevations, between one and

264

Cavendish

Cavendish himself had no more inclination to travel
above the earth than across it, but he did have use
for people who went up in balloons.

Water

Pneumatic chemistry was recognized as an
indispensable part of chemistry, at least from
Cavendish's publication on factitious air in 1766. In
1771 the industrial chemist James Keir brought out
an English translation of Macquer's Dictionary of
Chemistry, originally published in 1766, and to
ensure that the dictionary reflected the "present
state of chemical knowledge," Keir added material
from Black, MacBride, and Cavendish. 32

By 1773 the president of the Royal Society,
John Pringlc, could give a discourse on the history
of pneumatic chemistry." The field of pneumatic
chemistry at the time Cavendish returned to it was
summarized by Tiberius Cavallo, in his Treatise on . . .
Air in 1781. This book of over eight hundred pages
was about a subject, distinct airs, that can hardly be
said to have existed before Cavendish's work just
fifteen years before.

In his paper in the Philosophical Transactions
for 1784, "Experiments on Air," Cavendish
reported his experiments on the production of
water from the explosion of common air with
inflammable air. We might expect that just as Black
and ( lavendish showed that the ancient element air
consisted of distinct airs. Cavendish would show
that the ancient element water is another
combination of airs, but that is not what Cavendish
did. 1 le did not bring into question the elemental
notion of water, even as his experiments laid the
factual basis for our modern understanding of w ater
as a chemical combination of gases. His way of
talking about water was ambiguous as to its
elemental or compound nature, but that question
was beside the point. His purpose was to explain
the phlogistication of common air, and his discussion
of water in this connection was unambiguous.
Because of the subsequent importance of water in
this work, we refer to Cavendish's paper of 1784 on
the phlogistication of air as his paper on the
"condensation" of water, his term (alternative
terms used by his contempraries include "com-
position" of water and "decomposition" of air); at
the same time we recognize that the condensation
of water was incidental. Several paths led to
Cavendish's experiments on the condensation of

water from exploding gases. The obvious one was
his previous work on gases, in particular, his
recognition of inflammable air as a distinct air in
1766. Another was his study of latent and specific-
heats, another his study of electricity, and yet
another was his experiments on common air using
the eudiometer, which led directly to the
experiments in his paper of 1784. The wider setting
was the investigations from the late 1770s of the air
lost during phlogistication by Priestley, Lavoisier,
and C Jar! Wilhelm Scheele. Cavendish's immediate
stimulus was the work of Priestley together with
his fellow experimenter John Warltire.

Cavendish's purpose in "Experiments on
Air" was "to find out the cause of the diminution
which common air is well known to suffer by all
the v arious ways in which it is phlogisticated . . . " M
It was a question as important as it was difficult;
Priestley had varied opinions on it, and other
chemists had other opinions." Cavendish's answer
went back to an experiment he performed in late
June or early July 1781 labeled: "Explosion of
Inflam. Air by El. in Class Globe to Determine Mr
YYarltires Experiment." 36 Warltire, as reported by
Priestley, electrically fired a mixture of inflammable
and common air in a closed vessel, noting the
generation of heat and light and a loss of weight,
which Warltire attributed to the escape of a
ponderable matter of heat. Warltire and Priestley also
noted a deposit of dew inside the vessel, to which
they did not attribute a fundamental significance. S1
Cav endish repeated Warltire 's experiment, obtaining
dew and heat but not a loss of weight. The latter
fact could not have surprised him, since he
believed that heat is motion not ponderable matter.
Given that he found dew, he could not have been

three kilometers, the amount of oxygen in the air over London was
virtually constant. Brimbleeombc, "Earliest Atmospheric Profile." 365.

,2 Pierre Joseph Macquer, A Dictionary of Chemistry Containing the
Theory /nut Practice of That Science .... trans. J. Keir. 2 vols. ( I <ondon,
1771) l:i, iv.

"John Pringle, "A Discourse on the Different Kinds of Air,
Delivered at the Anniversary Meeting of the Royal Society,
November 30. 1 773." I'T M (1774): 1-31, Supplement at the end of
the volume.

i4 llcnr\ Cavendish, "Experiments on Air." /'/' 74 (1784):
1 1 9-69; Set. Pap.Z: 161-81, on 161 .
"Cavallo, Treatise, 419-20.

"•Cavendish, "Experiments on Air." Cavendish Mss. II, 5: 115.
In the same year. 1781, Cavallo too took notice of Warltire's
experiment, which he thought elegant and the outcome of which he
thought very remarkable. Cavallo. Treatise, 666.

"Joseph Priestley. Experiments and Observations Relating, to
Various Branches of Natural Philosophy . . . (London. 1781 ) 2:395-98.

Copyrighted malarial

Mr and Water

265

surprised by the heat, since he had found that
condensation, the change from a gas to a liquid,
always generated heat, though what was involved
here was more than a simple change of state. 38 He
would probably have been surprised by the dew
itself; in any event he recognized its significance.
He repeated the experiment, observing that all of
the first and about one-fifth part of the common air
lost their "elasticity" and "condensed" into the
dew lining the vessel. This dew had no color, taste,
or smell; "in short, it seemed pure water." 39
Cavendish determined that the lost fifth part of the
common air was the new air Priestley had
announced in 1774, and which was discovered
independently by Scheele, "dephlogisticated air,"
our oxygen. He inferred from the experiments on
the condensation of water that dephlogisticated air
is "in reality nothing but dephlogisticated water, or
water deprived of its phlogiston," and that
inflammable air is in all probability "phlogisticated
water" or "water united to phlogiston." When the
two airs combine with the help of an electric spark,
their water condenses out. 40 In this explanation,
phlogiston is treated as elemental and dephlogisti-
cated and inflammable airs as compounded. To the
question of what causes the decrease in common
air when it is phlogisticated, Cavendish's answer
was that the dephlogisticated part of common air
combines with inflammable air and is then no
longer air but pure liquid water.

To be complete. Cavendish identified the
other part of atmospheric air, the already
phlogisticated air, our nitrogen: phlogisticated air,
he said, is nitrous acid united to phlogiston. 41
These several relationships between phlogiston,
dephlogisticated air, phlogisticated air, and water
constitute Cavendish's understanding of air.

By giving essentially his theory of chemistry-,
Cavendish was now in open disagreement with
formidable adversaries, Priestley, Kirwan, Watt, and
Lavoisier. Having abandoned his earlier probable
identification of phlogiston with inflammable air,
Cavendish was at variance with the chemists who
had adopted the same interpretation, Priestley and
Kirwan. Finding no role for fixed air in the
phlogistication of common air, Cavendish contradicted
Kirwan, from whom Cavendish would soon hear.
His differences with Watt and Lavoisier were more
fundamental. Watt, in a paper read before the
Royal Society, proposed that water was a union of

dephlogisticated air and inflammable air or phlo-
giston, deprived of their latent heat. In his paper
the year before on the freezing of mercury,
Cavendish had given his differences with Black on
the subject of latent heat. Now it came up again in
chemistry, and Cavendish again rejected latent heat
because he did not believe that heat was a kind of
matter instead of motion; even the use of the term
"latent" led to "false ideas" in chemistry. He
rejected Watt's theory in chemistry because he-
rejected latent heat. 4 - He was circumspectly opposed
to Lavoisier's proposal to eliminate phlogiston from
chemistry and to introduce in its stead oxygen
(Cavendish's dephlogisticated air). Conceding that
nature seemed to be about as well explained on
Lavoisier's phlogistonless chemistry as on his own,
Cavendish said that there was a circumstance that
persuaded him that phlogiston still held the
advantage. On the phlogiston theory, plants gave
off phlogiston when they were burned, and it
seemed obvious to Cavendish that plants were
more compounded than their ash; on Lavoisier's
theory, the ash, containing oxygen, was the more
compounded. But Cavendish thought it would be
"very difficult to determine by experiment which
of these opinions is the truest." 4 '' So this otherw ise
strong paper by Cavendish ended with equivocation
and an admittedly weak defense of the advantage
of phlogiston over phlogistonless chemistry.

Over the next four years, Cavendish pub-
lished three more papers on chemistry. The first
was in reply to Kirwan, who accepted that Caven-
dish had succeeded in showing that dephlogisti-
cated air was turned into water by its combination
with phlogiston, but who thought that Cavendish
had gone too far in claiming that in the phlo-
gistication of air, water was a/ways generated and
fixed air never. Cavendish had ignored all the
proofs Kirwan had given of the involvement of
fixed air, which played the role of a universal aeid
in Kirwan's theory of chemistry. The importance
Kirwan attributed to fixed air was a common idea
at the time, and Cavendish had taken pains at the

'"This analysis draws on Russell McCormmach, "Henry
Cavendish: A Study of Rational Empiricism in Eighteenth-Century
Natural Philosophy." [sis 60 (1969): 293-306. on 305.

"Cavendish, "Experiments on Air," 166-67.

■"'Cavendish. "Experiments on Air," I71-7.V

"Ibid., 170-72.

«Ibid., 173-74.

«Ibid., 179-80.

266

Cavendish

PLA'I E XI. Apparatus for Experiments on Air. For converting phlogisticated air (nitrogen) into nitrous (nitric) acid. Cavendish passes a spark
through air trapped in the bent tube shown in Figure 1. The tube, first filled w ith mercury, is inverted into two glasses containing mercury. Figures
I and 3 show small-bore tubes used to insert the nitrous air into the bent tube. "Experiments on Air." Philosophical Transactions 75 ( 1 785): 384.

beginning of his paper on the condensation of
water to show that fixed air was not involved;
Cavendish would hear from others on this point. 44
Cavendish responded; Kirwan answered back, but
Cavendisli let it pass this time. 45

Nitrous Acid

In 1785, in a paper of the same title,
"Kxperiments on Air," Cavendish made a thorough
examination of a point from the first paper: if a
trace of phlogisticated air was admitted into a
mixture of inflammable and dephlogisticated air
and detonated, dilute nitrous acid rather than pure
water was deposited. In a new series of experi-
ments he showed that the inflammable air was
unnecessary for this result. When fired by
electricity, phlogisticated air and dephlogisticated
air alone yielded nitrous acid, and if they were
mixed in the right proportions, the gases were
entirely condensed into nitrous acid. 4 ' 1 This
research exactly paralleled Cavendish's research on
the condensation of water from dephlogisticated air
and another air, inflammable air.

Lavoisier with two colleagues tried in vain
to repeat Cavendish's experiment on the con-

version of the two airs into nitrous acid by means of
the electric spark; Cavendish could not imagine
why they failed except for "want of patience."
Martin van Marum wrote to Cavendish in 1785 —
the year of van Marum's great electrical machine,
the largest in existence — about his similar failure to
obtain Cavendish's result with the electric spark.
Cavendish did not know why van Marum failed
either, though he thought that the apparatus might
be faulty. 47 Instead of guessing what went wrong in

4J Jean Senebrier, writing to Cavendish about his paper on the
condensation of water, brought up a single experiment that seemed
to show that fixed air results from the phlogistication of the pure part
of common air. Letter to Cavendish, 1 Nov. 1785, Cavendish Mss,
New ( Correspondence.

4, Henry Cavendish, "Answer to Mr. Kirwan's Remarks upon the
Experiments on Air," PT 74 (1784): 170-77; Sci. Pap. 2:182-86.
Cavendish's papers contain an extract, in Blagden's hand, of a letter
from Kirwan to ( )rell that appeared in ( Irell's journal discussing the whole
unresolved dispute. "Extract of a Letter from Mr. Kirwan in London
to Professor Crell (Chem. Annals, no. VI p. 523. June 1784),"
Cavendish Mss X(b), 10.

■"•Henry Cavendish, "Experiments on Air." /'/' 75 (1785):
372-84; Sci. Pap. 2: 1 87-M4. on 1 <> 1 .

47 Martin van Marum to Henry Cavendish, 6 Jan. 1785;
Cavendish to van Marum, undated, draft. Cavendish Mss, New
Correspondence. Cavendish published this correspondence in his
paper, "On the Conversion of a Mixture of Dephlogisticated and
Phlogisticated Air into Nitrous Acid by the Electric Spark," PT 78
(1788): 261-76; Sci. Pap. 2:224-32, on 231-32.

Copyrighted malarial

Mr and Water

267

experiments by others, Cavendish again demon-
strated what was right in his own. He asked the
clerk of the Royal Society, George Gilpin, to repeat
the experiment before some persons who were
familiar with the subject. On several days in late
1787 and early 1788, the witnesses gathered, ten at
least, most of whom came to each part of the
experiment: Banks, Blagden. Heberden, Watson,
John Hunter, George Fordyce, J. L. Macie, and
Johann Casper Dollfuss; William Higgins and
Richard Brockelsby came on a day when an
"accident" happened, and Cavendish did not list
them in his paper. 4 * Gilpin worked Nairne's patent
electrical machine a half hour at a stretch, obtain-
ing two or three hundred sparks a minute, whereas
Cavendish had only worked his machine for
ten minutes at a time. Details of method aside,
Gilpin's experiments confirmed Cavendish's. They
were the substance of Cavendish's last publication in
chemistry.

Cavendish's contributions to chemistry were
widely separated, the first in 1766 and the second
almost twenty years later, in 1783-85. The earlier
work, on factitious air, was fundamental to the
development of chemistry as a science: it opened
up a field of discovery of new airs, and it
demonstrated a rigorously quantitative approach,
essential for keeping track of these elastic fluids,
the nature of which is to escape. The later work, on
the condensation of water and nitrous acid, was
only one, if important, contribution at a time of
rapid advances by many contributors. The field by
then had clear objectives, established techniques,
and a theoretical direction (or directions, Lavoisier's
being opposed to the phlogistic chemistry
Cavendish worked within). The production of
water from airs was observed by several chemists at
about the same time. From the point of view of the
chemists involved, what was important was who
did it first. What was important for chemistry was
the model — -a repeat for Cavendish — of experi-
mental research in the chemistry of airs. To have
read and grasped Cavendish's paper of 1785 was to
have taken a master class in the art of experiment.
Jean Senebrier, an experimentalist who wrote
penetrating works on the experimental method,
wrote to Cavendish after reading his recent papers
on airs that he admired Cavendish's "exactitude":
"You are a master and a great master in the difficult
art of making experiments." 49

Atmosphere

If we look at Cavendish's later work as a
kind of chemical meteorology, we see that it takes
on an additional significance. The title Cavendish
gave to his two major chemical papers in 1784 and
1785, "Experiments on Air," did not refer to a
single, universal air, because he did not believe in
one. Rather it referred to common air, that of the
atmosphere. He, along with other leading chemists,
understood that this air consisted of two "distinct
substances," dephlogisticated air and phlogisticated
air (we continue to use the terminology of
phlogistic chemistry), neither of which was
understood when Cavendish took up his researches
with the eudiometer. He intended his paper of
1784 to "throw great light on the constitution and
manner of production of dephlogisticated air." 50 In
his paper of 1785, he wrote that "we scarcely know
more of the nature of the phlogisticated part of our
atmosphere, than that it is not diminished by lime-
water, caustic alkalies, or nitrous air; that it is unfit
to support fire, or maintain life in animals; and that
its specific gravity is not much less than that of
common air"; we do not know if there are "in
reality many different substances confounded
together by us under the name of phlogisticated
air." By experiment Cavendish showed that the
phlogisticated air of the atmosphere was only one
substance. 5 ' Joining together his knowledge of
pneumatic chemistry-, affinity, heat, and electricity.
Cavendish clarified the understanding of the
atmosphere. In 1785 Blagden sent his brother three
papers by Cavendish and Watt, which taken
together seemed to Blagden "fully to explain the
nature of our atmosphere." 5 -' Blagden noted that
the most important of the three papers was
Cavendish's on the origin of nitrous acid (and not
the one on the condensation of water), for it
showed that the greatest part of the atmosphere "is
nothing but that acid in aerial form." Blagden's

■"■Higgins and Brockelsby came on V> Jan. 178H; Cavendish
refers to the "accident" of that day but not to the people attending.
T. S. Wheeler and J. R. Partington. The Life and Work of William
Higgins, Chemist (1763-1X25) (New York: Pcrgamon, I960), ?,?>, 66.

■'''Senebrier to Cavendish, 1 Nov. 1785.

^"Cavendish, "Experiments on Air," 161.

^'Cavendish, "Experiments on Air," 192-93.

^-Charles Blagden to Thomas Blagden, 8 Dec. 178.S. Blagden
Lcttcrbook. Yale.

268

view of Cavendish's work w as usually Cavendish's
own. Priestley wrote to Cavendish that his
experimental work on phlogisticated air was "one
of the greatest, perhaps the very greatest, and most
important, relating to the doetrine of air." 5 ''

Phlogisticated air was examined first by
Cavendish, but he did not publish on the subject.
Daniel Rutherford, Black's and Cullen's student,
wrote his medical dissertation in 1772 at the
I niversity of Edinburgh on Black's fixed air, which
Rutherford called "mephitic air." In the course of
his experiments, Rutherford isolated another
similar air, phlogisticated air, which we call
nitrogen. Rutherford's dissertation was published,
and so, properly, he is given credit for discovering
nitrogen, but many years earlier Cavendish had
studied this air. In a paper written for a
correspondent, "you," w ho had shown him a letter
from Priestley on what Priestley called "mephitic
air," by which Cavendish understood Priestley to
mean air that "suffocates animals," Cavendish said
that "in all probability there are many kinds of air
w hich possess this property." Cavendish knew of at
least two airs of this kind. Black's fixed air and
common air in which something has burned, or
"burnt air." Cavendish gave his correspondent the
results of an earlier experiment of his, in w hich he-
had determined by specific gravity and other
characteristics that a sample of burnt air was not
fixed air. This paper by Cavendish is undated, but
Priestley gav e a v ersion of it in his paper of 1772. S4

There was an extraordinary follow-up of
Cavendish's study. In his experiments on phlogisti-
cated air. Cav endish was unable to eliminate a tiny
"bubble" in his apparatus, l/12()th of the whole.
This minuscule residue, which Cavendish described
as an experimental error, was consequently, and
consequentially, noticed by William Ramsay. The
occasion was the "water controversy," which had
resulted in George Wilson's biography of Henry
Cavendish, a secondhand copy of which Ramsay
had bought when he was a student. Years later, in
the 1890s, Ramsay recalled the pertinent passage
and drew it to the attention of Lord Rayleigh. Ramsay
and Rayleigh were working on the same problem, a
third-decimal difference in density of the nitrogen in
the atmosphere and the nitrogen produced chemically.
Together they determined that Cavendish's residue-
was a new gas of the atmosphere, the chemically inert
gas argon. Nitrogen, they found, was actually a

Cti-vendish

mixture of nitrogen and argon, which finding opened
up a new epoch in the study of the atmosphere. The
discovery of argon inspired Ramsay to write a history
of the gases of the atmosphere, in w hich he observed
that of all the experimenters in this field. Cav endish
was "undoubtedly the greatest.""

As we have seen, Cavendish was guided in
his experimental study of the atmosphere by the
phlogiston theory', to which he gave his own twist.
His interlocked interpretations of phlogiston,
phlogisticated air, dephlogisticated air, nitrous acid,
and water provided a satisfactory understanding of
the atmosphere, which we can look upon as a late
triumph of the phlogiston theory.

New Chemistry

The progressive development of exact
techniques in chemistry, as in other parts of natural
philosophy, would have happened even if there
had been no "chemical revolution." Cavendish's most
important work in chemistry had been to advance
the methods of examining airs, in workaday
chemistry. But there was a chemical revolution —
that is accepted by most historians of chemistrv
even as they disagree about what it was, what its
boundaries were, and w hat place the overthrow of
phlogiston had in it 56 — and consequently the
historical interest in Cavendish's work has been
largely in relation to that event. Cavendish's
contribution to chemistry was substantial, though it
was not among the conceptual changes that mark
the chemical revolution. By contrast Lavoisier set a
course for himself that required a break with the
chemistry he learned, which was what every
chemist then learned, phlogistic chemistry. From

^Joseph Priestley to llenrv Cavendish. 30 Dec. 1784.
( lavendish Mss. New Correspondence. Priestley's letter was in reply
in Cavendish's, w ritten late in 1784, which summarized the main
points of what would become the published paper (if the following
year. Henry Cavendish to Joseph Priestley. 20 Dee. 1 784, draft.
Cavendish Mss. New Correspondence. These letters are published
in Scientific Autobiography of Joseph Priestley, 239-42, quotation on 241.

M Henry Cavendish. "Paper Communicated to Dr. Priestley,"
Cavendish Mss. Mise. Seheele too studied this gas. perhaps as early
as 1771. but he did not publish on it until 1777. K. L. Seott,
• Rutherford, Daniel." DSB 12:24-25.

"Ramsay. The Gust* of the Atmosphere, 143. Bruno Kisch, Scales and
Wrights: A Historical Outline (New Haven: Yale University Press, 1965), 8.

56 Arthur L. Donov an. "Introduction," in The Chemical Revolution:
Essays in Reinterpretation, cd. A. Donovan, ser. 2, vol. 4 of Osiris.
published in 1988 by the History of Seienee Society, 5-12. on 5-6.
Robert Siegfried, "The Chemical Revolution in the History of
Chemistry." ibid.. 34-50. on 34-35.

Copynqliie

Mr and Water

269

the early 1770s he consciously worked to make a
revolution in physics and chemistry. Twenty years
later he had done nothing less, or, depending upon
one's interpretation, he had completed the first part
of that revolution. For a change of this magnitude
to have taken place in chemistry, a number of
developments were needed. The most obvious of
these was pneumatic chemistry, which replaced the
ancient idea of elementary air by chemically active,
distinct gases, or the gaseous state. Lavoisier's
chemistry was built upon the new understanding of
gases. Cavendish's production of water from airs, or
gases, was particularly important for Lavoisier, who
saw immediately that Cavendish's experiments
implied that water was a compound. That gave
him the answer to the critical question of what
happens when metals were dissolved in acids: the
inflammable air, or hydrogen, that was released did
not come from the metals, as the phlogiston theory
taught, but from the dissociated water. This was
the understanding he needed to bring about his
reconstruction of chemistry. The same experiments
did not, and could not, lead Cavendish to the new
chemistry, since he had a perfectly satisfactory-
explanation of them in the phlogiston theory.
Other developments leading to the revolution in
chemistry Cavendish did not participate in. For
example, he did not accept at face value the
increase in weight of burned and calcined bodies.
The bizarre phlogistic explanations of this increase
gave Lavoisier strong arguments for the absurdity
of phlogiston. In order to build as well as destroy,
Lavoisier had to work out a new understanding of
chemical compounds and a new nomenclature to
express it, and he had to win disciples. These
things, of course, he did. His Trade elementaire de
(hemic in 1789 would instruct the next generation of
chemists in the new chemistry. 57

Cavendish had strong feelings about the
changes Lavoisier was bringing about. We know
this because of private remarks in a correspondence
between Blagden and Cavendish when Blagden
was away from London on the French and Fnglish
triangulation project in 1787. The French crossed
the Channel bearing anti-phlogistic chemical
publications for Cavendish and other Fnglish
scientists, and these included a copy of the Methode
de nomenclature rh'imiqiie written by Lavoisier and
his colleagues, just out. From Dover Blagden wrote
to Cavendish in London that he had the book and

would hold it if Cavendish planned to join him or
forward it to Banks's where Cavendish could pick it
up. 58 Because of foul weather. Cavendish did not
go to Dover, with the result that he and Blagden
discussed the nomenclature by letter. Cavendish
understood that the proposal for the systematic
renaming of the substances of chemistry 7 was a
move to impress the new theory on chemistry. The
language and the theory could not be separated
and could even be seen as one and the same thing.
Nothing, Cavendish said, serves "more to rivet a
theory in the minds of learners than to form all the
names which they are to use upon that theory." If
this precedent were to succeed, every chemist with
a new theory could present it together with a new
language, and no one could understand what was
being said without learning the theory. Moreover,
every experimental advance in chemical composition
would be followed by renaming. A systematic
nomenclature did not lead to clarity, as the pro-
posers believed, but to "confusion," which was a
"great mischief." Cavendish, however, had no opposi-
tion to naming uncommon neutral salts by the names
of their components because there were so many of
them. Apologizing to Blagden for this uncharacteristic
"long sermon" on the "present rage of name-
making," Cavendish said that he did not believe
that the nomenclature would take hold in any case. 5 ''
Blagden's reaction was much the same. The
authors of the chemical nomenclature had been
seduced by the Linnean natural history, Blagden
wrote to Cav endish, and the analogy was false. The
objects studied by natural history remained the same
over long periods, but in chemistry, discoveries
came so rapidly that names would have to change-
constantly. Like Cavendish, Blagden saw "little-
danger that the sy stematic names will be adopted." 00
Cavendish and Blagden were typical of British

"Changes that underlay the chemical revolution arc
summarized in William II. Brock. The h'outtina History of Chemistry
(London: Pontana, 1992). 84-85.

"Berthollet's memoirs were delivered to Blagden at Dover lis
Lcgcndrc. but the Nomenclature ihimir/ue was brought to him in
London, and he had already left London for Dover. So it appears
that the copy Blagden had in Dover was meant for Banks. None ot
this matters since Cavendish received a copy from Lavoisier. Charles
Blagden to Henry Cavendish. 16 Sep. 1787. Cavendish Mss \(b). I V
Charles Blagden to Claude Louis Berthollet, 17 Nov. 1787, draft,
Blagden Lettcrbook, Royal Society, 7:85. Henry Cavendish, n.d.
/Sep. 1 787/. draft. Cavendish Mss. Misc.. .SW. l',i/>. 2:324-26.
''Cavendish to Blagden. /Sep. 1787/. draft.

'"Charles Blagden to Henry Cavendish, 23 Sep. 1787.
Cavendish Mss X(b). 14.

270

Cavendish

scientists in their response to the nomenclature.
There was a kind of British bluffness about their
belief in common-language chemistry'. Soon after
the nomenclature, another good idea, the French
metric system, was proposed, which prompted
Cavendish's scientific friend George Shuckburgh
to appeal to British "good sense" and "preserve,
with the measures, the language of their fore-
fathers": he would "call a yard a yard and a pound a
pound."'' 1

W hat is striking about the exchange between
Cavendish and Blagden over the nomenclature is
that the dissatisfaction it conveys was directed
solely at systematic naming and not at all at the
content of the theory it expressed. Cavendish not
only did not oppose systematic chemistry, he insisted
on it; a chemistry that was not regularly connected
would have held no interest for him. To his chemical
researches as to all of his scientific undertakings, he
brought a strong theoretical need and competence.
That phlogistic chemistry was systematic was
evident to the chemists working within it, as it was
to one who had just abandoned it in favor of
Lavoisier's new system. L. B. Guyton de Morveau.
To the upholder of phlogiston Kirwan, Guyton
wrote that until now, Kirwan's phlogistic "system"
was "without doubt both the most scientific and
the most ingenious that has been proposed. " 6Z The
kind of system that Cavendish did oppose was
systematic naming, where it seemed to prejudice
the theoretical questions. Other proposals of
chemical nomenclature and shorthands around this
same time were met with skepticism by Blagden.
The fate of phlogistic chemistry did not seem to be
the issue with Cavendish. Blagden told Cavendish
that Lavoisier had "ably combated the arguments
of the phlogistic chemists,"' 14 as if Blagden
excluded Cavendish from the phlogistic chemists,
as perhaps he did. Blagden and Berthollet had
been in regular correspondence as representatives
of their national societies, and by 1785 Berthollet
was an anti-phlogistonist. That year Blagden wrote
to Berthollet that the English had not given up on
phlogiston; he mentioned its warm advocacy by
Kirwan, "but with Mr. Cavendish it is a doubtful
point."'' 5 Whether the "old hypothesis of p" is right
or Lavoisier's that dephlogisticated air is a "simple
substance," Blagden told Berthollet, is a "question
which I think cannot remain long undecided."'''' 'lb
William Cullen, Blagden wrote about the

"question now warmly agitated relative to the
existence of phlogiston"; whichever system, Stahl's
or Lavoisier's, was adopted, however, Cavendish's
work was of equal importance in either. 67 Two
years later, in 1787, in the same letter in which he
acknowledged receipt of the Nomenclature chimique,
Blagden told Berthollet that his memoirs had
answered the "principal objections made by the
supporters of the old doctrine of phlogiston." The
arguments of the new chemistry were so much
clearer than those of phlogistic chemistry that the
"combat must soon be at an end."' ,x In these letters
written at the turning point of the chemical
revolution Blagden was expressing his own opin-
ion, but we wonder to what degree, if any, it was in
opposition to the opinion of the chemist he worked
with daily. Cavendish.

If Kirwan is to be believed, by the time of
the new chemical nomenclature, Cavendish had
already given up on the old chemistry. In a postscript
to a letter to one of the authors of the Nomenclature
chimique, Guyton de Morveau, Kirwan wrote: "Mr
Cavendish has renounced phlogiston." Kirwan did
not give his source or elaborate, but what he said is
consistent with what Blagden had been saying to
and about Cavendish. The date was 2 April 1787,
Only a few weeks after van Marum had told
Lavoisier that he had rejected phlogiston.
Cavendish and van Marum were evidently the first
two scientists outside of France to abandon the old

'■'George Shuckburgh is quoted from his paper on weights and
measures in the Philosophical Transactions for 1798 in Kisch, Scales and
Weights, 19.

'-' This passage from Guyton 's letter is translated by the editors
of .1 Scientific Correspondence During the Chemical Revolution: Louis-
Bernard Guyton He Morveau duel Richard Kirwan, 1782-1802, ed. E.
Grison, M. Sadoun-Goupil, and I' Bret (Berkeley: Office for History
of Science and Technology, I'niversirv of California at Bcrkelcv.
1994), 33.

M "Dr. Black has just made a new chl nomenclature: I think he-
might have been better employed"; J. -I I. Hassenfrat/.'s chemical
shorthand was thought to serve no "useful purpose" in England; and
James Watt risked his reputation with his chemical algebra. Charles
Blagden to M.-A. I'ictet. 12 Feb. 1790. draft, and James Watt. 6 Dec.
1788. draft. Blagden Letterbook, Royal Society, 7:402 and 7:185.

"•Blagden to Cavendish. 23 Sep! 1787.

"Charles Blagden to Claude Louis Berthollet, 21 May 1785,
draft, Blagden Letterbook. Vale.

"Charles Blagden to Claude Louis Berthollet, 24 May 1785,
draft, Blagden Letterbook, Yale.

'-Charles Blagden to William Cullen, 5 July 1785. draft. Blagden
Letterbook. Vale.

''"Charles Blagden to Claude Louis Berthollet. 17 Nov. 1787,
draft, Blagden Letterbook, Royal Society, 7:85.

Air and Water

271

chemistry. 69 There would soon be many. For
example, the Jacksonian professor at Cambridge,
Isaac Milner, who lectured on chemistry as well as
on natural philosophy, saw the handwriting on the
wall; in his final lecture, in 1788, he discussed
Lavoisier's experiments and commented that the
"anticnt hypothesis of Phlogiston seems over-
turned at one Stroke, and a new and simple theory
substituted in its place — a Theory founded on
direct and satisfactory Experiments." 70

In 1788 an English translation of the new
nomenclature came out, but its adoption by users
of that language was relatively slow, given their
reluctance to use French words or their anglicized
versions and, in some cases, to parting with
phlogiston. Priestley never adopted the new
language nor gave up phlogiston. Black soon gave
up phlogiston, but he accepted the new language
only selectively and made up a partially new one of
his own. In the 1790s, however, the French
nomenclature was commonly used in Edinburgh as
in London. 71 (In a letter in 1794 Blagden spoke of
Thomas Beddoe's apparatus and the "dephlogisti-
cated dog" inside it; he crossed out "dephlogisti-
cated" and wrote instead "oxygenated." Scientifically
correct speech had to be practiced. 72 ) Cavendish,
late in life, used Lavoisier's new names on occasion. 73

Water Controversy

The "water controversy" arose from the
following events. In 1781, as we have just seen,
Cavendish repeated Warltire's experiment on the
electrical sparking of inflammable and dephlogis-
ticated air, determining that the resulting dew was
pure water. Me informed Priestley, who repeated
the experiments and reported them to Watt. In a
letter that circulated among members of the Royal
Society, Watt concluded that water is a compound
of inflammable and deplogisticated airs. Hearing
about Cavendish's experiments and Watt's
conclusions from Blagden on a trip to Paris in 1783,
Lavoisier promptly did experiments of his own and
wrote up an account of them. 74 Then, in 1784,
Cavendish's paper on the condensation of water
appeared. Cavendish, Watt, and Lavoisier, the
principals in the water controversy, all had different
interpretations of the meaning of the experiments,
and from the point of view of the history of
chemistry, that is all that matters. Cavendish's and
Watt's differing phlogistic interpretations we have

already given; Lavoisier's was the modern interpre-
tation: water is produced by the combination of
hydrogen and oxygen. If the water controversy had
been about these different interpretations, it would
have been a controversy of the usual kind in
science, but this one was about character. It began
with the Swiss scientist Jean Andre Deluc, who
had been living in England for ten years. This
expert on meteorological instruments, whose work
Cavendish respected and with whom he did
experiments, was away in Paris at the time
Cavendish's paper on the condensation of water
was read in London, but he heard about it, and
when he returned he asked Blagden for a copy of
the manuscript to read. Deluc then wrote to his
friend Watt that Cavendish had put forward Watt's
discovery "word for word" without mentioning
Watt. Watt, who believed the worst of Lavoisier,
was prepared to believe that Cavendish had stolen
his discovery as well. Blagden, who had carried the
news about water to Lavoisier, was appalled by
Lavoisier's claim, and he took a variety of
measures, public and private, to set matters
straight. Lavoisier stood corrected; Lavoisier after

,,9 If, as Kirwan said. Cavendish gave up phlogiston, we still do
not know his views on Lavoisier's theory. We do. however, know \an
Marum's. To Lavoisier on 26 l-'eb. 1 787, Van Martini wrote that he
had "adopted almost entirely your theory, having rejected phlogiston,
which I regard at present as an insufficient and useless hypothesis . . ."
To Kirwan on 13 Dee. 1787, Guyton de Morveau wrote: "You know
that M. Van Martini has decomposed water by electricity, repeated
the experiment w ith nitrous acid of M. Cavendish, and that he has
also abandoned phlogiston." Van Marum's letter to Lavoisier of 26
Feb. 1787 is quoted, p. 175, n. 8, and Kirwan's letter to Guyton of 2
Apr. 1787 and Guyton's to Kirwan of 1.5 Dec. 1787 are published, pp.
165-67 and 171-77, in .1 Scientific Correspondence During the Chemical
Revolution.

7 "L. J. M. Coleby, 'Isaac Milner and the Jacksonian Chair of
Natural Philosophy," Annals of Science 10 (1954): 234-57, on 256.

''Maurice Crosland, Historical Studies in the hinguage of Chemistry
(London: Heinemann, 1%2), 193-206.

■ 'Charles Blagden to Ceorgiana. duchess of Devonshire, 4 Jan.
1794, Devon. Coll.

7, In computations made probably around 1800, Cavendish used
"hydrogen" and "oxygen": Henry Cavendish, "Kxperiments on Air,"
Cavendish Mss II. 5:390. Blagden and Cavendish discussed a paper
by Humboldt on the eudiometer, and Cavendish wrote to Blagden
with his second thoughts about it. In this letter Cavendish uses
Lavoisier's name for phlogistieatcd air (our nitrogen) "azote." This
would have been at the end of the 1790s; some ten years had passed
since his fulminations against Lavoisier's new chemical nomen-
clature. Henry Cavendish to Charles Blagden, 18 Dec. /no year/,
Blagden Papers, Royal Society.

"The day after Lavoisier had repeated Cavendish's experiment,
Blagden wrote to Banks that Lavoisier made the experiment after
Blagden's account of it from Priestley's paper and ( Cavendish's verbal
information. Letter of 25 June 1783, copy. BM(NH), DTC 3:184-86. It
seems that word of Priestley's experiments had already reached Paris.
Henry Cucrlae, "Lavoisier, Antoine-Laurent," OSB 8:66-91, on 78.

272

all did nor covet a discovery so much as all of
chemistry, and the experiments on water had told
him how to get it. 7 ^

The passion behind the water controversy
was decidedly Watt's. He was an inventor and
engineer for whom a stolen idea was stolen income,
and he took pride in his scientific understanding.
He told his informer Deluc that he did not depend
on the favor of "Mr. C: or his friends; and could
despise the united power of the illustrious house of
Cavendish, as Mr. Fox calls them." 7 ' 1 Cavendish was
a rich man with a mean spirit, was how Watt put
it. 77 Watt's outrage was fueled by a resentment of
privilege that was nor uncommon in England at the
time (nor in France, which was only five years away
from irs political revolution). He began to cool
clown w hen he got hold of Cav endish's paper and
saw that his and Cavendish's conclusions were not
the same after all, and he and Cav endish later met
on friendly terms, in Birmingham, where Watt not
Cavendish was king, to examine steam engines.
The trouble-maker in all this was Deluc, whose
motives are unclear, though resentment over
Cav endish's rejection of his ideas in a committee of
the Royal Society may hav e been one of them. It
may have been a case of bad conscience too, since
at just this time Deluc allegedly was appropriating
Joseph Black's discoveries in latent heat as his own,
with Watt's unwitting help; 78 he had reason to
ingratiate himself w ith Watt, and it might also have
helped for him to believe that Cavendish was the
true blackguard of science. Blagden's complicity in
the water controversy was built into his relation-
ship with Cavendish; intimacy with him was his
scientific passport, while at the same time his
zealous regard for the reputation of Cavendish
made him vulnerable. Latter-day champions of
Watt made Blagden a scapegoat, but he was guilty
not of the unfairness and v enality he was charged
with but only of neglect of his ow n better interest.
Nor was Cav endish guilty of exploiting Blagden's
dependent position to get him to commit fraud on
his behalf. Priestley comes off as the almost
completely innocent party. But with the remote
exception of Deluc, there was no malice on the
part of anyone. When the steps leading to the
dispute are examined one by one, this conclusion
seems inescapable: the basic cause of this "contro-
versy," as opposed to the scientific debate, was the
casual way scientific information was communi-

Cavendish

cated in the eighteenth century. The discovery of
the nature of water was timely, and the stakes were
high, so that otherwise tolerable exchanges by
letters, conversations, visits, meetings, with their
indifferent datings, could, with proper incitement,
seem darkly suspicious. As it turned out, precisely
because there was also controversy of the usual
kind, different interpretations of the same
experiments, there was glory to go around. A
second water controversy occurred long after the
participants of the first were dead. The revival was
prompted by the secretary of the French Academy
I). F. J. Arago's eloge of Witt with its revisionist
history of the discovery of water. This controversy
was fueled by passion of another kind, familiar in
the nineteenth century, nationalism. It was the
occasion for Cavendish's unpublished scientific
work to begin to be made public, and so it had that
v alue if probably no other.

Keeping Up with Chemistry

In 1784 the German chemist Lorenz Crell
launched the Chemische Annalen, a monthly journal
that replaced the quarterly one he had been
editing. Cavendish took great interest in this
journal, which had the support of German chemists
and favored, as he still did, the phlogiston approach
to chemistry. Cavendish was soon in touch with the
editor about subscriptions. It was no simple matter
to obtain foreign journals in England in the
eighteenth century, as Cavendish's negotiations
with Crell bear out.

The water controversy had begun, and as a
result Cavendish and the Chemische Annalen had
gotten off on the wrong foot. In his new journal
Crell had published two accounts of the discovery

"H)ur main source here is George Wilson. The Life of the
Honourable Henry Cavendish (London. I84(i). which is primarily about
the w ater controv ersy. James Watt to Jean Andre Deluc, 6 Mar. 1784.
in Correspondence of the Late James Watt on His Discovery of the Theory oj
the Composition of Water, ed. J. I'. Muirhead 1 1 .ondon. 1846), 4,H— +9.

''Jean Andre Deluc to James Watt. 1 Mar. 1784, in
Correspondence of the Late James Watt, 48— 19.

77 Still fuming, Watt again identified Cavendish as "a member of
the illustrious house of Cavendish, worth above £ 100,000. and does
not spend £ 1000 per year. Rich men may do mean actions . . ."
James Watt to Mr. fry of Bristol. 15 May 1784. Correspondence of the
I, iite James Watt. 6] .

'"According to an account of the controversy between Black and
Deluc in the Edinburgh Review in 180.5, as quoted in Paul A.
Tunbridge, "Jean Andre De Luc," Notes an/I Records of the Royal
Society of London Id ( 1971 ): 15-.?.?. on 27-2H.

A ir and Witter

27.1

concerning air and water in which Lavoisier was
named the discoverer and Cavendish the con-
firmer. Crell wrote to Banks for more information
about Cavendish's work. Banks passed the letter to
Blagden, who replied to Crell with a "short history
of the discovery," setting Crell straight by
correcting the claims of Lavoisier, who had "sup-
pressed part of the truth." Blagden complimented
Crell on the quick publication of translated extracts
from Cavendish's paper containing the true
discovery and for Crell's correct dating of the paper,
1784, instead of 1783, as the separately printed
cover of the paper had erroneously put it. This first
letter from Blagden to Crell included the latest
scientific news from Britain, meant to entice Crell
to join in a regular scientific exchange between the
two countries. 71 '

Crell proposed to publish Blagden's short
history of Cavendish's discovery. Although Blagden
had not intended it for the public, he had no
objection, since it was "strictly true." He only hoped
that Crell's German translation of it would rather
"soften than strengthen the expressions," since
however poorly Lavoisier had behaved in this
affair, he was "upon the whole a very respectable
character & eminent as a philosopher." Again
Blagden enclosed scientific news, in keeping with
his invitation to Crell. The news had to do with "Mr
Cavendish, whose name I shall so often have
occasion to mention in this correspondence," but this
time it had to do with Cavendish's new work on the
freezing of mercury rather than the history of his old.
Definitely from this point on, and no doubt from
the beginning, the guiding hand behind Blagden's
correspondence with Crell was Cavendish's.* 0

The German chemist knew of Cavendish's
rank but little of English titles. "The Honourable
Henry Cavendish (not My Lord)," Blagden
corrected him. The Honourable Henry Cavendish —
and this was the point of Blagden's writing in this
instance — "desires to become one of your
subscribers." To this end, Blagden said, Cavendish
had given directions to the post office to ensure
that he received the journals promptly. 81 It proved
a futile hope.

Six months later, on 4 July 1786, Blagden
wrote to Crell that the postmaster at Amsterdam
had told him that some of the packets Crell had
sent were held up at Amsterdam because of their
large size and were probably irrecoverable. Crell

had sent them not by post but by stagecoach or
wagon, conveyances which were not "connected
with but in opposition to the Post." By post
Cavendish succeeded in receiving a few issues of
the Chemische Annalen and its supplement, the
Beitriige, and Blagden instructed Crell to send
Cavendish the rest by post as well. When after
three months the issues had not yet arrived in
London, Blagden complained to the post office and
then to Crell: "Mr Cavendish pays many times the
original value of the work to have it in this manner
quick by the post; but the various delays have
entirely frustrated that object."*-' The post office
proved not to be a better way. Two years later, at last,
the business of delivery was settled and the
correspondence on it ended: "Mr Cavendish finds it
more convenient to get the Ch. Annalen," Blagden
wrote to Crell, "in the common way, tho' a little later,
than to be perplexed with the post office; he . . . w ill
not give you any further trouble on the subject." 83

But complications continued. There was
the matter of payment for the subscription, of how
much and to whom. Blagden told Crell to send
directions and to appoint some person to collect
Cavendish's money. In addition to Cavendish there
were others in Britain who wanted to subscribe, for
example, the chemist Kirwan, and Banks, who
wanted to subscribe both for his own library and for
the king's, and the journal could not be sent to
everyone "through the same channel under one
cover." Then, in addition to Crell's journal, there-
were other publications by Crell that Cavendish
wanted: from his German bookseller. Cavendish
had ordered Crell's A/tsaa/t/ aits den iietien
Entdeckungen, but the bookseller had disappointed

;, 'Charlcs Hidden to Lorcnz Crell. 28 Apr. 178.S. draft. Blagden
Letterbook, Yale.

""Charles Bladen to Lorcnz. Crell. 2 Dec. 1785. draft. Blagden
Letcerbook, Royal .Society, 7:738. The historical part of Blagden's
letter was translated in Crell's journal in 1786. It was translated back
into English by Muirhead, Correspondence of the Ijitr Jumrs Watt,
71-74. and reprinted in Wilson. Cavendish, 362-63. Wilson dates the
letter 1786, p. 144, but it was written in early 1785.

"'Charles Blagden to l.orcnz Crell. 20 Jan. 1786. draft. Blagden
Letterbook, Royal Society, 7:742.

"-Charles Blagden to Lorcnz Crell. 4 July, 12 Aug., and 13 Oct.
1786, drafts; Charles Blagden to Charles Jackson at the post office,
10 Oct. 1786. Blagden Letterbook, Royal Society. 7:7. 26. 44. and 45.
By July 4. Cavendish had received the first and second issues of the
.\nn/ilin and the fourth issue of volume I of the BcitrSge. On 13
October, he was still waiting for the third through si\th issues of the
Annalen and the first through the third issues of the Beitrtige.

"'Charles Blagden to Lorcnz Crell. 4 Apr. 1788, draft. Blagden
Letterbook, Royal Society. 7:137.

274

Cure en dish

him. Crell offered to copy out the materia}
Cavendish wanted, but instead Cavendish asked
Crell to send the entire volumes directly. 84

To send scientific publications from Britain
to Ccrmany was no simpler than the reverse.
Blagden sent a copy of Cavendish's latest paper to
Crell in a packet, which he gave to William
Herschel, who was going to Cottingen to erect one
of his telescopes as a present from the king. From
Gottingen, Herschel was to forward the packet by
the nearest conveyance to Helmstadt, where Crell
would receive it. Blagden apologized to Crell: "It is
extremely difficult to get an opportunity of sending
you any thing from England, otherwise you should
be furnished sooner with such publications." 85

Blagden and Crell corresponded about the
science of the day while stripling with the slow
business of getting scientific publications from one
country to the next. Blagden wrote to Cavendish
about his last letter from Crell, which mixed
scientific news and subscription delays: "I hope
you got Mr. Heydinger to read Crell's letter; there
was something about your subscription from his
journal which he allows to have been already paid,
& an account of the freezing of /mercury/ by
natural cold in Russia, perfectly conformable to Mr.
Hutchins's experiments. . . Be so good as to open
cv read or get read any letters that you think may
contain news." 86 Correspondence was the surest
and quickest way of exchanging scientific news,
but it was not a substitute for complete publica-
tions. Cavendish's protracted exchange with Crell,
through Blagden, shows his determination to keep
posted (and as promptly as possible) on develop-
ments in the subject of his researches.

Exactitude

We have suggested that Henry Cavendish's
early chemical correspondent was John Hadley, the
fourth professor of chemistry at Cambridge.
I ladley had taken his teaching seriously, but since
the chair was not endowed, he received no salarv
and had to depend on student fees, a problematic
source since chemistry was not a subject students
needed for the examinations. Hadley left Cambridge
to practice medicine in London in 1760, but he did
not give up his chair, perhaps intending to return.
He died unexpectedly in 1764, whereupon the
chair again became available. The person elected
to it that year was Robert Smith's protege Richard

Watson, second wrangler in 1759 and now fellow of
Trinity. His main qualification was his willingness
to take the impecunious position, since he readily
conceded that he knew nothing about chemistry.
But he worked hard to learn it, and he was soon
giving experimental lectures, teaching students
privately, and working in his own laboratory. His
Iectuting began in the same year as Cavendish's
first published paper, on factitious air. in 1766, and
his approach to chemistry was clearly based on the
precise quantitative experimental work reported in
that paper. His Plan of a Course of Chemical Lectures,
published in 1771, makes that connection explicit.
To a bright young person like Watson taking up
chemistry in the 1760s, the promising direction
could be seen, correctly; it was the chemistry of
Cavendish, and of Black and Lavoisier, that of
quantitative exactness. 87

For its logogram, the Cavendish Society, a
nineteenth-century chemists' publishing club,
picked the glass vessel in which Cavendish deto-
nated gases to obtain water. This appatatus, which
appeared on the title page of Wilson's biography of
Cavendish, was a kind of eudiometer, and it was
fitting, but the Society might have chosen another
apparatus or instrument just as well. Although it
lacked the urn-like simple beauty (or the
controversial relevance) of the water vessel, the air
pump might have stood for "Cavendish"; or just
the pump's pear-shaped £;lass bulb for holding
mercury would have been sufficient. In his
experiments on phlogisticated air and nitrous
acid — experiments of the same kind as those on
water — Cavendish needed the best vacuum he
could get, and so a good air pump. As with all the

M Blagden to Crell, 4 July and 12 Aug. 1786.
"'Blagden to Crell, 4 July 1786.

"Charles Blagden to Henry Cavendish, 23 Sep. 1787,
( lavendish Mss X(b), 14. As Crell knew. Cavendish would have been
interested in the confirmation of Hutchins's experiments, which he-
had directed. Cavendish evidently could not read Crell's script and
relied on Blagden's account of the letters.

"'Through political connections. Watson got a 100 pound grant
from the king for his chemical teaching, but when the well-endowed
regius professorship of divinity was vacated by Thomas Rutherforth,
Watson preferred it and was appointed to it in 1771. He published
several papers in the Philosophical Transactions. His paper of 1770 is a
good example of his method, a quantitative study of specific-
gravities: "Experiments and Observations on Various Phaenomena
Attending the Solution of Salts." PT 60 (1770): 325-54. Between
1781 and 1787, he published five popular, elementary volumes on
chemistry, entitled Chemical lissays. L. J. M. Coleby, "Richard
Watson, Professor of Chemistry in the University of Cambridge.
1764-71," Annals of Science 9 (1953): 101-23. on 102-7, 121-22.

A ir and Water

275

instruments he used, his success with the air pump
was based on his grasp of the physical principles, as
we now illustrate. With his greatly improved air
pump of the 1750s, John Smeaton claimed a
rarefaction of air of 1000 or 2000 times instead of
the previous limit of less than 150. Implicit
confidence was placed in his claim until the
instrument-maker Edward Nairne discovered a
fallacy, to which he was led after obtaining
incredible rarefactions of 100,000. By making
comparisons with other standard gauges, Nairne
saw that the error lay in Smeaton's new gauge, the
pear-shaped bulb, but Nairne did not know the
reason for it. He showed an experiment with the air
pump to Smeaton and other Fellows of the Royal
Society. Cavendish, one of the Fellows, explained
that the discrepancy was due to water vapor. To get
the gauges to agree, he said, the pump must be as
free as possible of all traces of water, since
Smeaton's gauge did not measure vapor pressure in
addition to the air pressure as other gauges did.
When Nairne took this precaution, the gauges
agreed and the rarefaction turned out to be a
believable 600. Cavendish's explanation rested on
his father's experiments, which showed that
whenever the pressure of the atmosphere on water
is reduced to a certain degree (which depends on
temperature), the water is immediately turned into
vapor and is as immediately turned back into water
on restoring the pressure. KX This change of state
affected Smeaton's gauge but not the others. Or
the Cavendish Society might have picked for its
logogram the thermometer, the instrument to
which Cavendish devoted more attention to than
to any other. But, we think, the logogram best
typifying Cavendish's technique in chemistry-
would have been the instrument of weighing, the
balance. Cavendish owned the first of the great
precision balances of the eighteenth century. 89
Built to Cavendish's plan, the balance is housed in
a rough wooden case standing about ten feet. Made
of sheet iron \9Vt inches long, the beam is supported
by steel knife edges rotating on steel planes, and
suspended from its ends by brass universal joints
are the weighing pans, measuring about a foot
across and placed about two feet beneath the beam.
The balance is capable of weighing to an accuracy
of 5 milligrams. 1 ' 0 It is not dated but the instrument-
maker's name is known to be Harrison. This is not
the John Harrison of the chronometers nor his only-

surviving son, William. He is very likely another
William Harrison, whom Cavendish employed as
his private instrument-maker in his later years.'"
Cavendish's weighings were persuasive. Blagden
said it with clarity in a letter at the time to his
counterpart in the French Academy, Berthollet:
upon exploding the two elastic fluids. Cavendish
found the weight of the two fluids to be equal to the
weight of the resulting water, and that settled it for
him; all that remained was for him to show that the
water was just that, pure water. 9 '

Lavoisier was usually a meticulous weigher
too, and like Cavendish he knew how to make
weighing effective in scientific arguments.'" When
Lavoisier learned of Cavendish's experiments on
water, he made his own with the assistance of the
great mathematical astronomer P. S. Laplace. So
caught up did Laplace become in chemistry that
Blagden inquired if what he was told was true, that
Laplace "had renounced his mathematical studies,
& was applying himself solidly to chemistry." 94
Thanks to the balance, chemistry was becoming a

""This clarification of the air pump occurred in 1776. It was
described by Nairne in a paper and by Charles llutton in his entry
"Air" in Mathematical and Philosophical Dictionary, vol. 1 (London.
1795), 56-57.

•"After Cavendish's balance. Jesse Ramsden made the next great
balance. Cor the Royal Society The next after that were the ones made
for Lavoisier by I'. Megnie and J. N. F'ortin. The innovations in
Cavendish's balance included the knife edges of the beam, the form of
the beam, the kind of suspension used for the pans, the lift for the
beam, the regulation of the sensitivity of the balance, and the index.
Maurice Daumas, Srientifie Instruments of the Seventeenth tine/ Eighteenth
Centuries, trans. M. I lolbrook (New York: Praeger, 1972), 134-35, 221-23.

"Ernest Child. The Tools of the Chemist (New York: Reinhold,
1940). 79.

"From Lord George Cavendish's list of Henry Cavendish's
servants at his death in 1810, we know that his instrument-maker's
name was William Harrison. At that time this William Harrison was
sixty-one. F^arlier he had worked for Ramsden. and so we can assume
that he was highly skilled. He was a source of one of the accounts of
Cavendish's death, in Wilson. Cavendish, 183.

'''Charles Blagden to Claude Louis Berthollet. 24 Oct. 1783,
draft. Blagden Lcttcrbook. Yale.

'"Lavoisier could be cavalier with weights too. When he and
Laplace burned oxygen and hydrogen to obtain water, they did not
keep track of the exact quantities of the gases, but they thought it was
safe to assume that the weights of the gases aiH | of (he water formed
from them were equal. According to Blagden, who witnessed it,
Lavoisier and Laplace's first experiment on the production of water
was "good for nothing as to determining the proportions of air &
water," and their only dependable result was the test of the purity of
water; they intended to repeat the experiment with the "necessary
precision," but the account of this first experiment was read before
the Academy of Sciences anyway. Charles Blagden to Joseph Banks,
25 June 1783, BM(NH), DTC 3.56-58. Henry Guerlac, "Lavoisier,
Antoine-Laurent," DSB 8:66-91, on 78.

""Charles Blagden to Claude Louis Berthollet. 8 Dec. 1789,
draft, Blagden Lcttcrbook, Royal Society. 7:377.

276

Cavendish

science exact enough to win over an astronomer.
When he read Cavendish's paper on water, Laplace
wrote to Blagden that Cavendish's experiments were
"infinitely important" and made with the "precision
and finesse that distinguish that excellent physicist" 95
This may be taken as a tribute from one astronomer
to another, both of* whom were working in chem-
istry. In the combination of skills Cavendish
brought to chemistry, he was, in effect, Laplace and
Lavoisier in one. What Laplace said of Cavendish's
work everyone else who commented on it said too:
it was work of exemplary precision. This way in
which Cavendish's work was distinguished was the
direction chemistry was taking in the late eigh-
teenth century, at w hich time already about a third
of all chemical publications were quantitative.
Cavendish's work, all quantitative (at the very
least, he measured what went in and what came
out) was widely read; of British authors in
chemistry, his and Priestley's were cited most often
at home, and in France his came only after
Priestley's.'"' It was appreciated that to communi-
cate productively with Cavendish it was good to
deal in quantities, if possible. The only letter con-
taining a quantitative table in Priestley's cor-
respondence is Priestley's first letter to Cavendish,
sent with the hope of beginning an exchange.'' 7
Cavendish's lasting work in chemistry was the
impetus he gave to the increasing precision of that
science (far remov ed from the misunderstandings of
the original water controv ersy and from the theater
put on by the sehoolish resurrectors of the water
controversy in the nineteenth century).

We conclude our discussion with an example
of precision in Cavendish's chemistry. The
meaningful recording of natural events in numbers
presupposes standards, vv hereby tests can be made,
allowing the numbers obtained by experiment or
observ ation to be compared. In all parts of science
in w hich he worked, Cavendish introduced standards;
since agreed-upon international standards of science
did not yet exist, he had to define his ow n. Typical
of Cavendish's practice is his weighings of acids
and alkalies, in which he used the concept of
"equivalent weights." This concept gained power
with the atomic theory of chemistry, but before-
then it served Cavendish very well, as before
Cavendish it had served others. The concept goes
back to the turn of the eighteenth century, to
Wilhelm Homberg, who is remembered for

introducing scientific chemistry into the French
Academy. Romberg's most important work was to
provide a way to arrange acids by their relative
strengths in neutralizing alkalies, which prov ided the
foundation of the understanding of neutral salts.''*
Working quantitatively, Homberg determined the
weights of various acids required to neutralize an
equivalent weight of an alkali, salt of tartar. w His
method was deficient in one respect: it ignored the
weight of gases absorbed and given off, as Black
pointed out in his work on magnesia alba." 10 James
Keir, the translator of \ lacquer's Dictionary of
Chemistry in 1771, said that most of Macquer's
errors "proceeded from the author not having been
acquainted with some very late discoveries,
especially those important ones concerning fixable
air." Keir corrected I lomberg's table of the
equivalent weights of four acids referred to salt of
tartar with numbers he took from Cavendish's 1766
paper on factitious air. 101 From the start of his
chemical researches. Cavendish recorded equivalent
weights and was evidently the first to use the word
"equivalent." 102 The substance Cavendish began
with, tartar, would seem to relate his direction in
chemistry to Homberg 's quantitative equivalents. 103
In his first publication, on factitious air. Cavendish
compared the weights of different alkalis required
to saturate a given quantity of acid to 1000 grains of
marble, his standard; by this measure, he ranked
alkalis by the quantities of fixed air they contained,
the subject of his research. 1 " 4 By the use of the
balance, Cavendish gave to chemistry an ordering,
which was one by quantity instead of by nomen-
clature. His equivalent weights prefigured the

' 5 Picrrc Simon Laplace to Charles Blagden, 7 May 1 785.
Blagden Letters, Royal Society. L.181.

'"■H. Gilman McCann, Chemistry Transformed: The Paradigmatic
Shift from Phlogiston to Oxygen (Norwood: Ablcx, 1<>7K). I45^t6.

'''Joseph Priestley to Henry Cavendish, 31 May 17X4. Cavendish
Mss. New Correspondence; published in Scientific Autobiography of
Joseph Priestley, 231-32.

'"Marie Boas Hall, "Homberg, Wilhelm or Guillaume," DSB
6:477-7K.

'"J. R. Partington, .1 History of Chemistry, vol. 5 (London:
Macmillan, 1962), 44-15.

""'Joseph Black. Experiments upon Magnesia Alba, Quicklime, unit
Some Other Alkaline Substitutes. 175.5 (Edinburgh: Alembic Club
Reprints. No. 1. 1898), 17-18.

"" Kntry "Acid" in Mactpier's Dictionary of Chemistry.

'"-'Partington. History of Chemistry 5:520.

""Ilcnrv Cavendish, "New Kxpcrimcnts on Tartar." Cavendish
Mss II, 2(b):13.

l04 Henry Cavendish, " Three Papers. Containing Experiments
on Factitious Air." in Sci. Pup. 2:92-94, 96.

Copy fig hi to

A ir and Water

J77

quantitative laws of chemistry, such as the laws of other parts of natural philosophy. Cavendish's
combining proportions, which were the next stage insistence on standards gave to his work its
in the development of chemistry. In chemistry, as in characteristic stamp of exactitude.

CHAPTER 4

cTVfercury

Cold

In the 1780s Cavendish returned to his
researches on heat at the same time that he
returned to those on chemistry, two fields which for
him always had a large overlap. He published three
papers dealing specifically with experiments on
cold; they rested on the totality of his understand-
ing of heat.

In the 1770s Pyotr Simon Pallas, a member
of the St. Petersburg Academy of Sciences,
published the results of his scientific explorations of
Siberia, 1 where he recorded a temperature of minus
70 degrees Fahrenheit. The mercury of Pallas's ther-
mometer froze to the glass stem, and Pallas noted,
as did Cavendish, that when the mercury- began to
melt the thermometer stood at minus 45 degrees. -
Pallas's discussion was perceptive; by this time-
some, but by no means full, clarification had been
brought to the subject of extreme cold.

Temperatures down to forty degrees below-
zero had been achieved artificially by Fahrenheit,
using a mixture of spirit of nitre and ice. 5 That, as it
turned out, was nothing compared to subsequent
accounts of artificial cold produced by freezing
mixtures and to other accounts of the extremes of
natural cold in the frozen parts of the earth, such as
the natural historian Johann Georg Gmelin's read-
ings with the mercury thermometer in Siberia of
120 degrees below zero. 4 (We can surmise w hy Lord
Charles Cavendish entertained his dinner guests
with experiments on the production of artificial cold
in 1750, for it was the year after the publication of
Gmelin's travels with his report of the incredible
cold of Siberia. William Watson, who reported on
Gmelin's observations, was one of the guests at
Charles Cavendish's dinner-demonstration. 5 )

At the beginning of his researches on heat,
in 1765, having just shown that cold is produced by
a change of state of substances, such as from ice to
liquid water, Cavendish examined the cold produced
by mixtures of snow and chemical reagents, record-

ing temperatures of around 20 degrees Fahrenheit.
He seems to have done nothing more with artificial
cold until ten years later, in January 1776, when
with a mixture of snow and aqua fortis he reached
25 degrees below zero. That still was not equal to
the natural cold that had frozen the mercury in
Pallas's thermometer in Siberia, but that was not
Cavendish's object either, since the experiments
he wanted done on the freezing of mercury had
already begun at Albany Fort, in Hudson's Bay.

The first clear evidence of the freezing of
mercury — the substance once regarded as the
essence of fluidity — was already fifteen years old.
In St. Petersburgh in December 1759, J. A. Braun
especially but also Aepinus and other academicians
witnessed mercury cold enough to be hammered and
drawn like any other metal. In the Philosophical
Transactions for 1761, William Watson published an
enthusiastic account of Braun's work on this "intirc-
ly new" subject.'' In a paper he gave to the St.
Petersburgh Academy — Cavendish made a long
extract of this paper — Braun told of repeating
Fahrenheit's experiments with snow and spirit of
nitre and being surprised when the mercury- in the
thermometer fell hundreds of degrees below zero.

'Pyotr Simon Pallas, Reise (lurch versrhiedenen Provinxen des rus-
sischen Retches in den Jahrrn I76H-I773, 2 vols. (St Petersburg, 1771-76).

-'"Account of Freezing of /mercury/ from Pallas Journey into
Siberia," extract in Cavendish's hand. Cavendish Mss 1 1 1(a). 15.

' Phis experiment by Fahrenheit was reported in Boerhaavc's
Chemistry. Cromwell Mortimer, "A Discourse Concerning the
I'sefulncss of Thermometers in Chemical Kxperiments . . .," PT 46
(1746-47): 672-95. on 682.

••Earlier, in our discussion of science at the time Henry Caven-
dish was studying at the university, we quoted Gmclin on his finding
of 120 degrees below zero on the Fahrenheit scale and W ilson's
acceptance of this remarkable cold. John Fothergill, "An Account of
Some Observations and Kxperiments Made in Siberia, Extracted from
the Preface to the Flora Siberica . . . /by/ Gmelin . . .," PTAS (1748):
248-62, on 258-60. William Watson, "A Comparison of Different
Thermometrical Observations in Siberia," PT48 ( 1 755): 108-9.

s Thomas Birch to Philip Yorke, 18 Aug. 1750, BL Add Mss
35597, f. 277.

'William Watson, "An Account of a Treatise in Latin, Presented
to the Royal Society, Intitled, De admirando frigore artificial!, quo
mcrcurius est congelatus, disscrtatio, &," PT52 (1761): 156-72.

Cavendish

PIRATE XII. Hudson's Bay Thermometers, ligurc 1 shows the ther-
mometer with the stem and bulb extending below the scale. Figure .1
gives a side view of the thermometer with the extended stem and
bulb inserted into a cylinder holding the mercury to he frozen.
Thomas I lutchins, "Experiments for Ascertaining the Point of Mer-
curial ( longclation," Philosophical Transactions 7.5 ( 1 783): ".570.

Braun could arrive at no consistent freezing point
of mercury. 7

Braun's experiments were repeated by
Thomas H urchins, governor of Albany Fort, in
Hudson's Bay, using the instruments and the
instructions sent to him by the Royal Society. In
the winter of 1774, Hutchins arriv ed at what Braun
had, frozen mercury, and the same inconclusive-
ness about the freezing temperature. There
seemed to be no instant of freezing, for without
changing appearance the mercury continued to fall
to below minus 400 degrees. Hutchins asked the
Royal Society for more tubes of mercury capable of
graduation to 1000 degrees below zero* 'The reason
why Hutchins's experiments had got no further
than Braun's was evident to the two persons who
had clarified for themselves the principles of latent
heat, Joseph Black and Cavendish. In a letter in
1779 about Braun's and Hutchins's experiments.
Black said that frozen mercury could not record its
own freezing temperature. To get around that
difficulty he proposed a new experimental arrange-
ment, which was to surround the thermometer
bulb containing mercury with a mercury bath. Since
metals solidify slowly from the outside inward, when
the mercury in the bath is frozen but that in the bulb is
still liquid, the thermometer can record the freezing
temperature. Hutchins informed the Royal Society
of Black's proposal, which he made the basis of his
next series of experiments. Cavendish had already
proposed the same apparatus. To Cavendish the
apparatus had suggested itself, since the experiment
on mercury was a repeat of his many experiments on
the freezing of metals. 'The reason why a mercury
thermometer cannot of its own measure the freezing
point of mercury is that, as Braun's and Hutchins's
experiments made clear, mercury contracts upon
freezing and thereby registers a heat far below its
freezing temperature. Black did not publish on this
subject, but this time Cavendish did.''

' This extract, in Cavendish's hand, in Cavendish Mss. Misc. is
an account of the experiments by several Petersburg academicians
following Braun's discovery; in English translation from the French
by James Parsons. "An Account of Artificial Cold Produced at
Petersburg: Bv Dr. Ilimsel. In a Letter to Dr. De Castro, F.R.S.,"
PT 51 (1760): 670-76.

" Thomas Hutchins, "An Account of Some Attempts to Freeze
Quicksilver, at Albany Tort, in Hudson's Bay. in the Year 1775: with
Observations on the Dipping-needle." PTbb ( 1 776): 174-81.

''Joseph Black to Andrew Graham on 5 Oct. 1779; letter
published by Thomas Hutchins in "Experiments for Ascertaining
the Point of Mercurial Congelation." PT73 ( 1 7KA): , 303-*370, on

Mercury

281

The reason for delegating the experiments
on cold to the Hudson's Bay Company was that it
was located in a cold climate, a better place than
(relatively) warm London. Cavendish drew up lists
of experiments on the freezing of mercury and the
expansion with heat of some other fluids and showed
them to the president of the Royal Society, Sir
Joseph Banks. 10 He then supplied Hutchins with
apparatus, with which Hutchins froze mercury by
exposing it both to freezing mixtures and to natural
cold, determining the freezing point both ways.
Hutchins's experiments were "very accurate," Cav-
endish told John Michcll." In his next paper on
the freezing of mercury, in 1783, Hutchins said that
his "excellent instructions" left him with "nothing
to do but to follow them." n

Hutchins's paper in the Philosophical Trans-
actions was followed directly by a paper by
Cavendish. Cavendish's "observations" on Hutchins's
experiments confirmed Cavendish's hypothesis,
which was that the great sinking of mercury in
thermometers in extreme cold is owing to the great
contraction of mercury. The earlier reports of the
great cold produced by freezing mixtures would, if
true, have been "really astonishing," but these were
actually reports about the contraction of mercury.
Submerged in freezing mixtures, Hutchins's ther-
mometer fell to 450 degrees below zero, but the
cold of the freezing mixture was never less than 46
degrees below zero. Referring to the results of his
much earlier, unpublished experiments on freezing
lead and tin. Cavendish said that he had "no reason
to doubt that the same thing would obtain in
quicksilver." I le referred also to his experiments on
the latent heat of water, presenting the investiga-
tion into the freezing of mercury as a direct
continuation of his work from the 1760s. 1 5

The only kind of instrument used in these
experiments was the thermometer. Although in the
experiments there were subsidiary considerations —
these were the burden of Cavendish's "observa-
tions" — the essential point was clearly and simply
demonstrated. The thermometer placed in the
container of mercury fell to minus 40 degrees
where it stayed, while another thermometer placed
in the freezing mixture of snow and spirit of nitre
continued to fall. The only interpretation could be-
that mercury freezes at minus 40 degrees. Hutchins
returned to England, meeting with Cavendish and
Blagden at Cavendish's house in Hampstead to

demonstrate the apparatus. 14 Hutchins then returned
them to the Royal Society, where in the best
practice of the time, in the presence of witnesses —
in addition to Cavendish, they were Banks,
Hutchins, Nairne (who made them), and Charles
Blagden — they were examined according to the
procedure recommended by the boiling-point
committee of 1777. By making corrections for the
boiling point on Hutchins's thermometers, the
adjusted freezing temperature of mercury was
declared to be minus 3H : A degrees or, in round
numbers, minus 39 degrees, in remarkably close
agreement with the modern value, minus 3N. ( S7
degrees. Mercury, upon freezing. Cavendish con-
cluded, shrinks by almost ^rd of its bulk, which is
also close to modern measurements. 1 ''

In 1789 Cavendish received a letter from
Richard Walker, who told of freezing mercury in
the presence of some Oxford professors. Walker
thought it was the first time it had been done in
Britain, and there is no reason he should have
thought otherwise." 1 Cavendish himself had frozen
mercury six years before at Hampstead, and at the
time he had shown it to Blagden and told friends
about it, but he did not publish the fact. 17
Cavendish had simply been doing experiments in
parallel to the more accurate ones done under his
direcrion in the Canadian cold by Hutchins.

on *305-*306. Black did not give his "reasons" for the inability of a
mercury thermometer to measure the freezing temperature of
mercury, but they obviously included the contraction of mercury.
Cavendish said that he had recommended the apparatus to the
president of the Royal Society, Joseph Banks, who had approved it.
Black had not known what Cavendish had done. Henry Cavendish.
"Observations on Mr. Hutchins's Experiments for Determining the
Degree of Cold at Which Quicksilver Freezes," PT73 (I783):303-28;
Sri. Pap. I: 145-60. on 149.

'" There are many related drafts in Cavendish's papers, most col-
lected in Cavendish Mss IIKa), 4 and 14. The first group ' s mainly
concerned with Hutchins's experiments published in 1 78.}, though it
contains some subsequent instructions sent in 1784. The second
group is concerned with the next series of experiments at Hudson's
Bay Company, conducted by John McNab, published in 1786 and
1788. In addition, there are unclassified papers on the Hudson's Bay
experiments in the miscellany of Cav endish's manuscripts.

"Henry Cavendish to John Michel!, 27 May 1 7K3. draft.
Cavendish Mss, New Correspondence.

l2 Hutchins, "Experiments for Ascertaining the Point of
Mercurial Congelation," *.M)4.

"Cavendish, "Observations," 146. 150-51.

'••Thomas Hutchins to Charles Blagden, n.d., "Monday
Morning," Blagden Letters, Royal Society, H.59.
'^Cavendish, "Observations," 148, 157.

"'Richard Walker to Henry Cavendish, 4 Jan. 1789, Cavendish
Mss, New ( Correspondence.

"Cavendish to Michcll, 11 May 178.V

282

(Cavendish was not done with artificial cold.
In 178.} he built an apparatus to produce cold by
rarefying air mechanically, 18 and over the next few
years Adair Crawford and Erasmus Darwin did
experiments with the same goal. 1 '' Wanting to
know the greatest cold that could be produced by a
freezing mixture of snow and various chemical
solutions. Cavendish requested more experiments
at Hudson's Bay, and these too he published, in
1 786 and 1788. This time his experimcnter-at-a-
distance was John McNab, master at Henley's
I louse, 1 ludson's Bay.

Cavendish was fortunate in his Hudson's Bay
experimenters, first Hutchins and then McNab,
who earned rare praise from Cavendish for their
"utmost attention and accuracy" and "great judge-
ment." They also showed extraordinary endurance;
McNab did his experiments in weather that reached
fifty degrees below zero. The new experiments
provided these results: cold "greatly superior" to
any yet produced (as opposed to claimed), and
insight into the "remarkable" way nitrous and
vitriolic acids freeze.-' 0

In a field, heat, which had only just begun
to be quantitative. Cavendish introduced the
"standard" measures he had first used in his experi-
ments on gases, specifying the strength of acids in
the freezing mixtures by the weight of marble they
could dissolve. I le made a table of specific gravities
of the acids corresponding to a range of strengths of
the acids at a temperature of sixty degrees; this
table corresponds with modern, theoretical values
to the third decimal.- 1 In his attempt to determine
the strength of acid that required the least degree
of cold to freeze, he made a discovery: there were
several "points of easiest freezing" of acids, points
of "inflexion" (corresponding to various hydrates). 22
( ia\ endish asked McNab to do another set of experi-
ments on the freezing of acids of varying strengths,
which became the subject of Cavendish's last paper
on heat, in 1788."

Heat

In 1810 Blagden was selected by Lord
George Cavendish and, presumably, by William,
duke of Devonshire, to write the obituary of
Cavendish for the "papers." Blagden began it with
the observation that Cavendish had made himself
master of "every part of Sir Isaac Newton's
philosophy." It is odd that in what follows Blagden

Cavendish

failed to mention Cavendish's work on heat,
although he made note of all of his other major
works. Odd, we say, because in none of his other
work was Cavendish known to have declared
himself publicly a more decided follower of
Newton than in his work on heat, and also because
Blagden assisted Cavendish in this work. If there is
a circumstance that might bear on Blagden's
neglect or forgetfulness in his obituary of his late
friend and colleague, it is that Blagden subscribed
to the popular material theory of heat, of which, as
we will see. Cavendish held a low, almost contemp-
tuous, opinion. 24

In 1783 Cavendish determined the freezing
point of mercury with the help of the concept of
latent heat, but he did not use the word latent,
deliberately not, because it "relates to an hypothesis
depending on the supposition, that the heat of
bodies is owing to their containing more or less of a
substance called the matter of heat; and as I think

'"The accounts of these experiments are published in Henry
Cavendish, The Scientific Papers of the Honourable Henry Cavendish, ed.
K. Thorpe. 2 vols. (Cambridge: Cambridge I nivcrsitv Press, 1921)
2:384-89.

"Charles Blagden to Erasmus Darwin. 14 Sep. 1786. draft.
Blagden Lcttcrbook. Royal Society. 7:54. Charles Blagden to Mrs.
Grey, 30 Jan. 1788, ibid.. 7:111.

J "IIenry Cavendish, "An Account of Experiments Made by John
McNab, at Henly I louse. Hudson's Bay, Relating to Freezing
Mixtures," PTlb (1786): 241-72: in Set Pap. 2: 195-213, on 19.S.

-' The comparison was made by Thorpe, in Cavendish, .SW.
Pap. 2:59-60.

--'Ibid.. 62.

- Henry Cav endish, "An Account of Experiments Made by Mr.
John McNab. at Albany Fort, Hudson's Bay, Relativ e to the Freezing of
Nitrous and Vitriolic Acids." PT7H ( 1 788): 166-81; in .SW. Pap. 2: 214-23.

M The complete draft of Blagden's obituary of Cavendish,
Blagden Collection. Royal Society, Misc Notes. No. 225. The obituary

was published in Gentleman's Magazine (Mar. 1810). 292. Publicly,
Blagden did not commit himself on the theory of heat: latent heat, "be
it a matter or motion," he wrote in "Experiments on the Cooling of
Water Below Its Freezing Point," PT 78 ( 1 788): 125-46, on 140. Even
in correspondence with colleagues, he was noncommittal, cautioning
Berthollet against speaking of the "matter" of heat instead of its
effects, since the "matter" had not been proven: Charles Blagden to
C. L. Berthollet, 5 June 1786, draft. Blagden Letters, Royal Society,
5. Privately, however, he was an advocate of the material theory. An
undated draft of a paper by Blagden, obviously addressed to
Cavendish, begins by recalling experiments on the freezing point of
mercury that Blagden carried out under Cavendish's direction and
goes on to discuss subsequent experiments of Blagden's own on
liquids cooled below their freezing points. In his explanation of this
phenomenon Blagden said that the particles of bodies have attracting
surfaces, a sort of polarity, and that interposed between the particles,
lessening the power of their attraction, is latent heat, which is an
"elastic fluid": Charles Blagden Papers, Yale, box 2, folder 23. The
discussion of heat in this section draws on Russell McCormmach.
"Henry Cavendish on the Theory of I leat," Isis 79 (1988): 37-67. We
acknowledge permission to use material: University of Chicago
Press: copyright 1988 by the History of Science Society. Inc.. all
rights reserved.

Mercury

JS.l

Sir Isaac Newton's opinion, that heat consists in the
internal motion of the particles of bodies, much the
most probable, I chose to use the expression, heat
is generated."- 5 He rejected Black's "latent heat" in
this his first public mention of the motion theory of
heat. This theory was then a contested, even
dubious theory, and his grounds for saying that it
was "much the most probable" he did not give, not
here nor elsewhere in print, though he did make
one more public pronouncement on the theory of
heat, which again was to object to the expression
and hypothesis of "latent heat." It occurred in his
paper on the condensation of water, which appeared
the following year, in 1784. Cavendish remarked
on a recent paper by James Watt concerning the
production of water, but Cavendish's point was
again the relationship between words and reality in
describing the phenomena of heat. In the passage
in question, now remembered not for its content so
much as for its part in the priority dispute, the
water controversy, Cavendish gave his reasons for
avoiding Watt's "language," Watt's "form of
speaking": "Now I have chosen to avoid this form
of speaking, both because I think it more likely
that there is no such thing as elementary heat, and
because saying so in this instance, without using
similar expressions in speaking of other chemical
unions, would be improper, and would lead to false
ideas; and it may even admit of doubt, whether the
doing it in general would not cause more trouble
and perplexity than it is worth." 26 So, in Cavendish's
judgment, the use of the expression "elementary
heat," referring to the material view of heat, would
lead only to false ideas, trouble, and perplexity.

The passage on Watt in 1784 and the
footnote on Joseph Black the year before were all
that Cavendish in his lifetime was to tell his
readers about the nature of heat. The scientific
manuscripts he left at his death were found to
contain two more references to Newton's theory of
heat, which we have pointed out earlier. One was
buried in a corollary to a theorem in a paper on the
theory of motion, a mechanical formulation of
Newton's theory that concluded with reasons why
the theory was "insufficient" in itself; the other was
in an experimental paper on latent and specific heats
that concluded with the observation that certain of
his experiments at first seemed to him "very difficult
to reconcile with Newton's theory of heat, but on
further consideration they seem by no means to be

so. But to understand this you must read the following
proposition." 27 Unfortunately, there the paper ends,
abruptly, without the promised proposition. Until
recently these references, one published and two
unpublished, were the only known explicit state-
ments by Cavendish on Newton's theory of heat. Since
it can be shown that Cavendish's understanding of
the nature of heat entered fundamentally into his
researches on factitious airs, the production of
water, and electricity, as well as his researches on
the freezing of mercury and on freezing mixtures in
general, 2 * what was missing was a fully developed
theory of heat, one comparable to his fully
developed theory of electricity.

In 1969 Lord Chesham, a direct descendant
of Henry Cavendish's heir Lord Ccorgc Cavendish,
put up for sale several manuscripts by Henry
Cavendish, including a theoretical paper, "Heat."
This paper was written in two drafts, one a revised,
nearly fair, copy with some crossings out. It gives, as
we would say, a rigorously mathematical, mechanical
theory of heat complete with the principle of con-
servation of energy, the concept of the mechanical
equivalent of heat, and applications of the theory to
the principal branches of physical science.-"' By any
reading, this paper must be seen as the culmination
of Cavendish's experimental and theoretical
researches. More than any of his other writings,
"Heat" testifies to Cavendish's concern with the
foundations of natural philosophy.

The idea of heat as motion had received
many formulations by Cavendish's time. To the
question of what it is that moves, a variety of

a Cavcndish, "Observations," 150-51.

Z6 Hcnry Cavendish, "Experiments on Air." FT 74 (17H4):
1 19-53; Sri Pap. 2:161-81, on 173-74.

27 Hcnry Cavendish, "Remarks on the Theory of Motion."
Henry Cavendish Mss VKb), 7; Sri Pap. 2:415-30, corollary 2 on
425-26. Henry Cavendish, "Experiments on Heat." ibid.. Misc.; AW.
Pap. 2:327-51, on 351 (the title is not Cavendish's). .

-"Russell McCormmach, "Henry Cavendish: A Study of
Rational Empiricism in Eighteenth-Century Natural Philosophy,"
/sis 60 (1969): 293-306.

''' The expressions "conservation of energy" and "mechanical
theory of heat" arc, of course, anachronistic and were not used by
Cavendish. The revised draft of "I Ieat" consists of forty-three pages
of text and notes, one page of diagrams with an accompanying page
of explanation, and one page of additions and alterations. Both drafts
of "Heat," along with several other Cavendish manuscripts, were
auctioned in London. With the exception of "Heat," they were
bought by the duke of Devonshire and added to Henry Cavendish's
scientific papers at Chatsworth. The original manuscripts of both
versions of "Heat" are located, under the reference M O 23, L 6, in
the Manuscript Division. Pre -Confederation Archives, Public Archives
of Canada, Ottawa.

284

(.<iz- en dish

answers had been proposed. The vibrating object
might be the ordinary particles of bodies, the air
and acid sulfur in bodies, the subtle ether, the
subtle fluid of fire or something else, or some
combination. Newton's authority was invoked in
support of more than one of these options, but to
Cavendish, New ton's theory meant the vibrations
of the ordinary particles of bodies. Many of the
examples in the queries of Newton's Opticks
invoked this view of heat, contributing to the
coherence of Newton's natural philosophy as it did
to that of Cavendish. 30

This, "Newton's," theory had a good many
arguments in its favor. The hypothesis of the
internal vibrations of the parts of bodies offered
plausible explanations of, for example, the heat
produced by chemical operations, hammering,
friction, and the absorption of light. But there were
also a good many well-known objections to the
theory. The heat and cold produced by dissolutions
and fermentations were seen as a challenging
difficulty long before Cavendish singled them out
in the "Remarks." Another, and to some a fatal,
difficulty was that the heat capacities of bodies
were found not to be proportional to their
densities, as the motion theory was understood to
require, f urther difficulties were discussed by the
first Jacksonian professor of natural philosophy at
Cambridge, Isaac Milner, in his lectures delivered
in 17H4-M, at the same time as Cavendish's work
on heat. One objection, according to Milner, was
that the vibrations of particles alleged to constitute
heat had not been proven to exist, and even if they
had, they would not correspond with the
phenomena. Another objection was that heat was
not observed to be proportional to motion, as it
would be if heat were motion. Another was that
when oil and grease were used to eliminate friction,
heat seemed to be eliminated too, although motion
was communicated to their particles. Milner listed
still more objections. Heat was observed to pass
slowly through bodies, as a liquid might, rather
than rapidly, as motion does. The motion theory of
heat implied that heat should not spread at all,
since the quantity of motion of a system of
particles is unaffected by their mutual actions and
collisions. It was said that the observed passage of
heat across a vacuum could not be explained by
motion since there are no intervening particles to
be set in vibration. And it was said that the

liberation of heat during the solidification of a liquid
was inconceivable if heat were motion. Milner had
answers to all of these objections, for he happened
to be a believer in the motion theory and a critic of
the opposing material theories. "The arguments
against this [motion] Theory have of late Years been
esteemed so numerous and weighty that it has almost
been given up by Philosophers," he said. It had been
given up "a little too precipitately," and he wished
that "somebody else had endeavoured to shew the
truth" of it by contrasting it with the fashionable
material fluid theories of heat. 31

The difficulties of the motion theory could
be grouped together as one general difficulty: new
mechanical ideas for the motion theory did not
keep pace with the rapid experimental development
of the science of heat in the late eighteenth century.
By contrast, the material theory of heat had
developed together with the experimental state of
the science, so that to many investigators, heat, as
an experimentally measurable quantity, appeared
better understood by the material theory than by
the motion theory.' 2

Heat, according to the material theory, was
one of a number of imponderable fluids, which, as
we remarked in our discussion of Cavendish's
electrical theory, had come to characterize British
speculative natural philosophy from about the
middle of the eighteenth century. Newton's ideas
about a subtle, elastic ether were a principal
inspiration for such fluids, though Newton was not
their creator. Cavendish contrasted "Newton's"
theory of heat with the theory of heat as a fluid. 33

The fluid of heat was usually taken to be
imponderable, subtle, and closely associated with

"'Robert K Schofield. Mechanism and Materialism: British Xafnral
Philosophy in an .It"' of Reason (Princeton: Princeton University Press,
1970), 13, 37. 48. 77-78, 84-85, 139, 160, 179, 18.V Schofield points
out, p. 183, that Newton "confuses the issue" in query 18. where he
speaks of the contribution of the vibrations of the ether to the heat of
bodies. To be cautious we should say that the theory of heat as the
vibration of the parts of bodies contributes to the coherence of
Newton's natural philosophy as presented in query 31. Newton,
Opticks (New York: Dover reprint. 1952), 348-49. 375-406.

"L. J. M. Coleby, "Isaac Milner and the Jacksonian Chair of
Natural Philosophy." Annals of Science 10 (1954): 234-57, on 242-52,
quotation on 244. The theory of heat that Milner preferred was this:
"Heal consists in a vibrating motion of the parts of bodies, and hire is
a bod} so heated as to emit light copiously"; ibid.

' Robert Fox, The Calorie Theory of Cases from Lavoisier to
Regnault (Oxford: Clarendon, 1971), 19,22-23.

"The imponderable fluid of heat drew on a variety of views
about ether, fire, repulsive forces, factitious airs, and the
imponderable fluids of electricity and magnetism. The proponents of

Mercury

285

fire, and its particles were usually assumed to repel
one another while they were attracted to the
particles of ordinary substances. This subtle,
repellent fluid had a single quantifiable property,
its amount, which accounted for most experiments
involving the transfer of heat. The fluid theory was
readily grasped, easy to apply, plausible, predictive,
and supported by the leading authorities of the day.
Black was thought to hold the fluid theory, as were
his students William Cleghorn, William Irvine, and
Adair Crawford, all of whom worked on the
subject. Cleghorn 's dissertation, De igne, of 1779,
which drew on the work of Black and his other
students, was particularly important for its early
advocacy and systematic presentation of the
material theory.- 14 Crawford, in his treatise Animal
Heat, also of 1779, advanced similar views, and
although his approval of the material theory was
tentative, he argued that it explained latent heat
better than did the motion theory. Shortly before,
in 1777, Lavoisier had published views on fire
similar to Cleghorn 's. While it was still common
then for authors not to commit themselves in print
to any particular theory of heat, most would have
agreed with Crawford that latent heat is better
accounted for by the material theory. It was within
this climate of thought that the new language of
heat was successfully introduced. 35

Researchers rarely needed to declare
themselves for one theory of heat or the other,
since they could get on with their experiments
very well without doing so. The classic case in
point is Lavoisier and Laplace's joint paper in 1783.
In this fundamental study in the emerging science
of calorimctry, the authors described both theories
of heat, side by side, without deciding between
them. Lavoisier almost certainly held the material
theory- of heat. What Laplace thought is uncertain,
and he was later to hold the material theory, but in
any event it was he who described the motion
theory in their joint paper. Unlike the standard
statement of the motion theory of the past, which
did little more than assert the identity of heat and
motion, Laplace's was mechanically precise. He
pointed out that just as in the material theory, in
which the quantity of fluid is conserved, in the
motion theory there is also a conserved quantity, vis
viva: by appeal to the law of conservation of vis
viva, he said, the communication of heat from one
body to another can be understood. When two

bodies of unequal temperatures are brought into
contact, the vis viva of the warmer body diminishes
while that of the cooler body increases until their
temperatures are equalized, at which time the vis
viva exchanged in each direction is identical. 36
This is the same insight as Cavendish's in his early
"Remarks on the Theory of Motion." In the
context of his later "Heat," the coincidence was
not only of ideas but also of timing: in May 1783
Cavendish's paper on the freezing point of mer-
cury, with its assertion of Newton's theory of heat,
was read before the Royal Society, and in June
Lavoisier and Laplace's paper on calorimetry was
presented to the Royal Academy of Sciences.
Cavendish's papers on heat were routinely sent to
Lavoisier and others in Paris through Blagden, and
on trips to Paris Blagden reported to Cavendish on

the imponderable fluid of heat, as of other imponderables, it should
be noted, also regarded their theories as "Newtonian"; Schofield,
Mechanism and Materialism, 157-90; P M. Ileimann, "Fthcr and
Imponderables," in Conceptions of Ether: Studies in the History of Ether
Theories, 1740-1900, ed. G. N. ( )antor and M. J. S. I lodge (Cambridge:
Cambridge University Press, 1981), 61-83, on 67-73. Arthur Quinn,
"Repulsive Force in England, 1706-1744," Historical Studies in the
Physical Sciences 13 ( 1982): 109-28, on 127; and Fox. Caloric Theory, 19.

,4 For a number of reasons Cleghorn rejected the motion theory
of heat. Nevertheless he followed "Newtonian principles closely" in
developing the mechanical consequences of a conserved fluid of
"fire," the particles of which repel one another and are attracted to
the particles of ordinary matter with a force that is different for
different bodies. He did not know the law of force or how to find it.
but he regarded its discovery as important. Although he gave a few-
simple equations, he did not give the theory a mathematical
development; Douglas McKic and Niels H. de V. Hcathcotc.
"William Cleghorn's De igne (1779)," Annals of Science 14 (1958): 1-82.
On the fluid theory of heat and those who held it: Fox, Caloric
Theory, 19-20, 22, 25; and Schofield, Mechanism and Materialism, 185.

'•' There w ere some rejections of the motion theory; e.g.. by Jean
Hyacinth de Magellan in 1780 and by Tiberius Cavallo in 1781; Fox.
Calorie 'Theory, 11, 28. Although Magellan accepted the material
theory, he rejected Black's terms "latent heat" and "heat capacity"
and introduced the neutral sounding term "specific heat" for heat
capacity and also the term "sensible heat" for the heat of the
thermometer. "Caloric." standing for the matter of heat, appeared in
1787 in L. B. Guyton de Morveau et al.. Melhode de nomenclature
ihimif/ue, the language of Lavoisier's new system of chemistry; Fox,
Calorie Theory, 6, 26.

"'The original publication of the often reprinted paper by
1 ,a\ oisicr and Laplace is Memoire sur la ehaleur. In a I'Aeade'mie Roya/e
ties Sciences, le 28 juin / 7<V.? . . . (Paris, 1783). Our discussion is based
on Henry Guerlac, "Chemistry as a Branch of Physics: Laplace's
Collaboration with Lavoisier," Historical Studies in the Physical Sciences
7 (1976): 193-76, on 244-50. Guerlac asks. p. 246. "how Laplace,
who of course used the principle of the conservation of vis viva in
treating the dynamics of the solar system, came to apply this
approach to the study of heat." He suggests that the idea came from
Daniel Bernoulli's Hydrodynamica of 1738, in which heat is associated
w ith the motion of particles of an aeriform fluid and the pressure of
the fluid w ith their vis viva. If Laplace did not read it there, Guerlac
thinks, he probably read the summary of it in J. A. Deities Reeherehes
sur les modifications de /'atmosphere of 1772. Larmor referred
Cavendish to the same early source, Daniel Bernoulli's Hydrodynamica.

Copyri

286

Cavendish

the latest experiments on heat there." We know
that Cavendish read Lavoisier and Laplace's
paper — as we would expect, given the subject and
the authors — and in it he found Laplace's state-
ment of the motion theory of heat, a reflection of
his own reasoning, if perhaps reasoning without the
same theoretical commitment. 38

It was from about the time of Cavendish's
and Lavoisier and Laplace's papers that the
material theory acquired its great following, which
would continue well into the next century. The
arguments about heat would usually be carried on
among the followers of the material theory them-
selves rather than between them and upholders of
the motion theory. By the end of the eighteenth
century in Britain, the material theory was all but
universally accepted. 39 The motion theory of heat
would seem to be going in the same direction as
the phlogiston theory of chemistry, into the
collection of historical curiosities of science.

Cavendish, exacting measurer of heat, was
naturally interested in any promising quantitative
ideas about heat. 40 At the time of his "Experiments
on Heat," as we have seen, he believed that
changes in specific heats are responsible for the
heats observed during changes of state. Among his
miscellaneous unpublished papers are derivations
of formulas for the absolute heat in a body and the
absolute zero of temperature, but why he made
them he did not say. In another miscellaneous
paper he gave an experimental disproof of the idea
that the absolute heats in bodies arc proportional to
their specific heats. 41 He was not alone in this
criticism, 4 - but this or any other criticism of
contemporary views on heat was not what was
wanting, which was a positive case for the most
probable theory. "Heat," the recently unearthed
manuscript, was to be it.

Cavendish knew what a persuasive case for
the motion theory required. He knew what Black
knew: Black had the common difficulty of being
unable to form an idea of the internal motions of
bodies that could account for the phenomena of
heat, but his main complaint against the motion
theory was that none of its supporters had shown
how to apply it to the entirety of heat phenomena.
The same complaint could not have been made
about the fluid theory, at least not after Cleghorn's
work. 4 ' With "Heat," Cavendish intended to supply
what was missing from the side of the motion theory.

"Heat" is a systematic presentation of New-
ton's theory of heat together with comprehensive
supporting evidence drawn from diverse fields.
With this, so far as we know his last, fundamental

"Cavendish's paper on the freezing of mercury, for example,
was sent by Blagden to Berthollei in multiple copies for Lavoisier
and other friends. Charles Blagden to Claude Louis Berthollei. 11
Apr. 1784. draft, Blagden Letterbook. Yale. From Paris, Blagden sent
news of experiments on the latent heat of water to Banks, with
instructions to pass the news along to Cavendish. Charles Blagden to
Sir Joseph Banks. 27 June 1783. draft, Blagden Letters, Royal
Society. B.166a.

,s In a letter to Lavoisier. Blagden included a comment written
out by Cavendish on Lavoisier and Laplace's memoir on heat:
Charles Blagden to Anroine Laurent Lavoisier (draft), 15 Sept. 1783.
Blagden Letterbook. '('ale.

19 Fox, Caloric Theory, l"->(>, 23, 104-5. There are well-known
exceptions, critics of the material theory of heat at the turn of the
century. Humphry Davy, Thomas Young, and Benjamin Thompson,
Count Rumford: ibid., 1(14. 115-16, and Schofield, Mechanism and
Materialism, 290-95.

Tor example. Cavendish was interested in certain quantitative
ideas advanced by Black's students. These included the ideas that
the heat or cold accompanying a change of state or a chemical
reaction is a consequence solely of a change in the heat capacities of
the bodies concerned; that the absolute quantities of heat in bodies
are proportional to their specific heats; and that from specific heats
the absolute zero of temperature can be calculated. Despite scant
experimental evidence, these views enjoyed a relatively long life
owing to the still rudimentary stage of calorimetrv. Fox, Caloric
Theory. 26-27.

"The first miscellaneous sheet is headed: "'That all the heat
which appears in bodies either by its being absorbed or united to
them or in its being again set loose from them whether it be by their
combinations or separation from each other or by any other change in
their nature depends intirely on the specific heat of each body & the
change of it": Cavendish Mss, Misc. This sheet contains formulas for
the absolute quantity of loose heat in a body and for the absolute
zero of temperature. The formulas assume that the absolute heat of a
body is proportional to its specific heat, an assumption which
Cavendish brought into question: the second miscellaneous sheet
bears the heading: "A compleat proof that the quantity of heat in
different bodies at a given temperature is not in proportion to their
specific heats." The proof, using Cavendish's experimental data,
begins with the statement: "'The mixing of sp. wine and water
affords a compleat proof that the absolute quantity of heat in
ditlerent bodies of a given temperature is not in proportion to their
specific heat for if it was the nearer the heat of Z bodies approach to
absolute cold the less should be the heat or cold produced by their
mixture whereas the heat produced by mixing spirit of wine & water
is greater when they are cold than hot"; Cavendish Mss. Misc.
Cavendish drew a line through the heading of this sheet; however,
there is a version of this same proof in nearly identical wording, in
Cavendish's hand, among Blagden's papers: Blagden Collection.
Royal Society. Misc. Notes.

42 llsing their recent measurements of specific and latent heats,
Laplace and Lavoisier in 1783 publicly criticized the rule for
calculating the absolute zero of temperature and the doctrine that
the quantities of heat in bodies are proportional to their specific
heats; Fox. Caloric Theory, 31.

43 For Black's difficulty: John Robison's edition in 1803 of Black's
I Ai tures o/i /he Elements of Chemistry, discussed in Schofield. Mechanism
and Materialism. 186-87. Cleghorn. after stating two principles from
which all of the effects of fire can be deduced, took up in turn the
principal "effects" of fire, eight in number: fluidity and evaporation,
inflammability, animal heat, heat from electric fluid, heat from
fermentation, friction, heat from mixtures, and heat of sun's rays;
McKie and Hcathcotc. "William Cleghorn's Deigne."

Mercury

287

theory, Cavendish brought the mechanical under-
standing of heat to a level that would not be
surpassed for over a half century. 44

Cavendish's paper starts out as a purely
mechanical investigation. 45 Cavendish divided vis
viva, defined as the mechanical effect of a body in
motion, into two kinds, "visible" and "invisible."
The visible vis viva is that of the center of mass of
a body undergoing progressive motion or of the
body undergoing rotation or both; the invisible vis
viva is that of the particles of the body mov ing
among themselves; the total vis viva of the body is
the sum of both. Cavendish further divided the
invisible vis viva into two parts, one "active," the
other inactive, the potential for becoming active.
His symbol s, standing for the active, is the actual
v is viva of all of the particles constituting the body;
his symbol S stands for one half the sum of the vis
viva that each particle would acquire by the
attraction or repulsion of every other particle in
falling from infinity to its actual position within the
body. Upon the understanding that the attractions
and repulsions between particles are always the
same at the same separations and different at different
separations, Cavendish derived the generalized law
of conservation of vis viva, active and inactive; the
quantity s - S cannot change as a result of the
motions of the particles among one another.

Cavendish identified the mechanical
quantities occurring in the propositions concerning
vis viva with the quantities occurring in heat. The
connection between the two is made through the
fundamental "hypothesis" of the theory: "Heat,"
Cavendish supposed, "consists in the internal motion
of the particles of which bodies are composed."
This internal motion is to be regarded as vibratory,
the particles being bound close to their place by
attracting and repelling forces. Cavendish identi-
fied the "active heat" of the body with the active,
actual vis viva s and the "latent heat" with the
potential vis viva - S and consequently the "total
heat" with s - S, the conserved quantity. "Sensible
heat" is what Cavendish called the heat of a body
as given by a thermometer, and it is related to the
active and latent heats through the constitution of
the body. With these terms, Cavendish had a
complete technical vocabulary for developing the
science of heat. 4 ' 1

It was then necessary to show that the
theory accounted for the facts of heat. Cavendish

first applied the theory to the communication of
heat and to specific heats. When two bodies,
isolated and unequally heated, are brought into
contact, one gives up heat and the other acquires it
until the sensible heat of each is the same. In the
exchange the total heat given up must be the same
as the total heat received, but just how this heat is
divided between the active and latent heats in the
two bodies depends on the weights of the bodies
and on "some function cither of the size of their
particles or of any other quality in them," for
example, the frequency of vibration of the
particles. 47 There are two reasons why one
substance requires a greater increment of total heat
than another substance to produce the same
increment of sensible heat:

First that some bodies may require a greater
addition of active heat than others in order to
produce the same increase of sensible heat; & 2 ntl| v
because in all bodies an alteration of sensible heat
can hardly help being attended with an alteration
of the quantity of latent heat. For as the bulk of all
or at least almost all bodies is increased by heat,
the distance of their particles must be alterd;
which can hardly fail of being attended by an
alteration of the value of S, that is of their latent
heat; & that alteration can hardly fail of being
greater in some bodies than others. 4x

The distinctions, based on experimental knowledge,
between sensible, total, active, and latent heats
provided Cavendish with the concepts he needed
to analyze complex heat processes in terms of
precise mechanical analogues.

**ln "Heat," Cavendish showed that the "effects" of internal
vibrations of bodies agree with seven classes of phenomena, which
arc largely the same as Cleghorn's in De igrn .

45 The mechanical propositions in "Heat" parallel those in the
"Remarks on the Theory of Motion," hut the arguments arc-
developed w ith greater thoroughness. E.g., whereas in the "Remarks"
Cavendish considered the interaction of only two particles in detail, in
"Heat" he did it for four particles before generalizing the result to any
number of particles: Cavendish, "Heat." 7-1 1.

4l, Cavendish. "Heat," 11-12. Cavendish did not formally
introduce a word for specific heat, though he mentioned the
"capacities for heat" of bodies (24, 41). His distinction between
active and latent heat in a body parallels the common distinction
made in the material theory between free heat in a body and heat
that is combined with it. or latent heat.

47 Cavendish, "Heat," 14-16. The explanation, which draws on
the mechanical propositions, is that different substances require
different quantities of active heats to raise their sensible heats by a
given amount: further, that the changes in sensible heats are
accompanied by changes in bulk, which translate into changes in the
separations of the particles and therefore into changes in latent heats
in ways that depend on the nature of the substances.

"Cavendish, "Heat," 16.

288

With his new theory, Cavendish no longer
saw his experimental findings on latent heat and
on chemical operations as possible difficulties for
Newton's theory but presented them as conse-
quences of it. He explained that when a body
changes from a solid to a liquid or from a liquid to
an elastic fluid, or when two bodies unite by their
chemical affinity, the particles undergo rearrange-
ment, and with it the latent heat and the active
heat required to produce a given sensible heat
change; since the total heat remains constant, the
sensible heat has to change. In addition. Cavendish
had the beginnings of a fundamental under-
standing of chemical reactions using measurements
of heat. 4 "

1 laving secured Newton's vibrational theory within
the subject of heat. Cavendish applied it to other
subjects, to optics first. " There can be no doubt,"
Cavendish said, that light is a body consisting of
extremely small particles emitted from luminous
bodies with extremely high velocity. When these
particles are reflected from a body, they are not
reflected by a single particle or by a few particles of
that body but by a great quantity of its matter, so
that, by mechanical principles, no perceptible vis
viva is communicated to the body. The same
explanation applies to the case of refracted light.
But where light is absorbed, its particles are
reflected back and forth w ithin the body until their
v elocity is no greater than that of the particles of the
body, "so that their vis viva will be equally
distributed between the body & them" and the
absorbing body w ill thereby acquire sensible heat. 50
The theory of heat is a theory about vis
viva, so that if the heating effect of light is to be
calculated theoretically, its vis viva must first be
known. For this purpose Cavendish turned to an
experiment by John Michell, which was widely
regarded as proof that light really consists of
streaming material particles. S| In this experiment,
inside a box w ith a window to the sun, a thin sheet
of copper was fastened to one end of a horizontal
wire, which was balanced by a weight at the other
end. Rays of the sun wete concentrated and directed
by a concave mirror so that they struck the copper
plate perpendicularly, resulting in a rotation of the
wite. s - From the observed speed of rotation and
other details of the experiment, and from the ideal
assumption that the light was perfectly reflected

Cavendish

from the copper, Cavendish calculated the momen-
tum and vis viva of the sunlight falling each second
on VA square feet of surface. To translate this result
into its mechanical effect, Cavendish calculated the
rate of vis viva of sunlight falling on that surface, an
enormous quantity, exceeding the work done by
two horses, that is, over two hofsepower. s,

It was well known that a plate of glass is
heated more than a plate of polished metal when
exposed to a fire and probably when exposed to
the sun as well. But since the metal absorbs more
light than the glass, according to Cavendish's
theory, it rathet than the glass ought to be heated

J, 'Ibid., 16-17. Recognizing the complexity of the problem of
chemical heats. Cavendish could only surest how the concepts of
active and latent heats might be applied, lie was seeking an
understanding, in terms of the heats involved, of why different
substances should mix and combine. Before this goal could be
realized, additional concepts had to be created, as they later would
be within the science of thermodynamics. That the heats of chemical
reactions were still the least understood of the phenomena of heat is
clear from Cavendish's lonn discussion of them, w hich he relegated
to a footnote, since the "reasoning is too hypothetical" and also not
central to the main purpose of the paper. The note reads: "w hen 2
substances which have a chymical affinity unite, it seems likely that
heat & not cold should commonly ensue; for unless the attracting
particles approach nearer together or the repelling particles recede
further, so as to increase the value of .S", one docs not easily see why
the 2 bodies should mix. But if .V is increased, the quantity of active
heat must be equally increased; & consequently the sensible heat
will in all probability be increased. This agrees with observation; for
except w here one of the bodies is changed by the mixture from a
solid to a fluid form, or from either of those forms to that of an elastic
fluid, I do not know a single instance of cold being produced by any
chymical mixture. But in mixtures in which this change of form takes
place, it is well know n that cold is frequently produced. Hut if this
increase of sensible cold proceeds from an increase of latent heat,
one does not well see as was before said why the mixture should take-
place; which might incline one to think that the cold which always
attends this change of form proceeded from the latter of the
abovementiond causes, or to more active heat beinf; necessary to
produce a given sensible heat w hen the body is in a fluid than a solid
form": ibid.. 17-19.

w lbid„ 18-20.

N. Cantor. Optics after Newton: theories of light in Britain
anil Ireland, 1704—1840 (Manchester: Manchester University
Press, 1983), 57.

■"-This experiment was described by Priestley, who said that
there w as no question but that the rotation was to be "ascribed to the
impulse of rhe rays of light": Joseph Priestley. The History and Present
State of Discoveries Relating to I ision, Ughl an/1 Colours ( 1 .ondon. 1 772 ).
3K7->W. It would be a long time before the cause of this rotation was
properly understood: S. (i. Brush and ( ). W. F. Kvcritt, "Maxwell,
Osborne Reynolds, and the Radiometer," Historical Studies in the
Physical Sciences 1 <lW>o): 103-25.

''''Since Michcll's experiment was done under glass, which
admits light rays but not heat rays. Cavendish pointed out that his
calculation of the total vis vita of the sun's rays was below the actual
total: Cavendish, "Heat," 24-25. For the value of 1 horsepower.
Cavendish assumed the work of a horse in a mill lifting 100 pounds
at the speed of 3 miles per hour: ibid., 22. This value is equivalent to
26,400 foot pounds of work per minute, w hich is somewhat lower
than our accepted value of 33,000 foot pounds per minute, as it was
defined by James Watt and Matthew Boulton.

Copyrighted material

Mercury

289

most by the light. To resolve this apparent eonfliet
with the theory. Cavendish referred to recent
experiments by Carl Wilhelm Seheele and Horaee
Benedict de Saussure on the newly discovered
"heat rays." Cavendish believed that heat rays, like
light rays with which they commingle in various
proportions, are material particles emitted by hot
bodies, and although their velocity is not known,
they too must communicate vis viva. But heat rays
differ from light rays too; not only do they not
excite the sensation of vision, but they arc-
absorbed by glass and are efficiently reflected by
polished metals, which is just the reverse of the
behavior of light. It is the heat rays, then, and not
the accompanying light rays, that warm the glass
preferentially. These new, invisible rays enabled
Cavendish to reconcile the facts with his theory of
heat; if the rays did not exist, the theory would fail. 54

According to Newton's theory, bodies are
warmed when they emit light and heat, but since
the repulsion by bodies of the particles of light and
radiant heat is accomplished by a relatively great
amount of matter, the vis viva of recoil in the
bodies is too small to detect. But the theory agrees
well with the familiar observation that as a body
grows hotter, it emits more light and heat. By
Cavendish's hypothesis, the particles of light and
radiant heat are bound to their natural places in a
body by the forces of attraction and repulsion of
the particles of the body, and when the particles of
the body are set in brisk vibration, the particles of
light and radiant heat are moved into positions
where they experience violent repulsion, flying off
from the body as free light and radiant heat. 55

Heat can be produced mechanically — for
example, by friction and hammering — and Cavendish
showed how this effect too agrees with the theory.
Since a violent force is required to produce heat,
the particles of the heated body must be displaced
or even torn away at its surface, and that in turn
alters the latent heat of the body, giving rise to
sensible heat. The same displacement or tearing
away of particles is responsible for the loss of
elasticity in the collision of two bodies or in the
bending of a body. Cavendish's analysis here of the
forces of particles was more problematic than in
some other applications of the theory, but on the
basic point he was "certain": if any visible vis viva
is lost by the rubbing, striking, or bending of
bodies, these bodies must acquire an "augmentation

of total heat equivalent thereto." 5 ''

Electricity is the science Cavendish had
worked over with the greatest theoretical and
experimental thoroughness, devoting the labor of a
decade to it without, however, having closely
examined the heat produced by electricity in
motion. Now, he said, he was going to "argue upon
the principles laid down in my paper concerning
the cause of electricity," his paper of 1771, to
derive a formula for the vis viva of electric fluid
discharged by an electric jar through a wire. 1 Ic
doubted that the particles of the electric fluid,
because of their extreme lightness, could com-
municate sufficient vis viva to the particles of the
wire to account for the violent heat of the wire. His
explanation of the heat is that the electric discharge
displaces the particles of the wire, greatly diminishing
the latent heat. The heat caused by electric
discharge is consistent with the theory, "though,"
Cavendish said, "it is an effect which I should not
have expected." 57

As the final application of his theory
Cavendish discussed the expansion and change of
state of bodies with heat. When a body is heated,
he reasoned, the increased vibrations of its particles
alter their mutual attractions and repulsions, which
in turn alter the size of the body. When the
vibrations become great enough, the attractions
and repulsions of the particles vary sufficiently for
the body to change its form and properties entirely,
which is what happens in evaporation and in
melting: the increased vibrations of the particles
diminish their adhesion, making bodies more fluid.
By the same reasoning Cavendish explained why
chemical decomposition and combination are
promoted by heat. 5 *

Experiment, for Cavendish, was never
distant from theory, and in three places in "Heat"
he made a note to himself to do an experiment
suggested by the theory, and in the rough draft he

Mlbid., 23-24.
"Ibid., 25-26.
*Ibid., 26-31, on 31.
"Ibid.. 32-38, on 41.

***il>id.. 38-39. Because of the increase of the vibrations of the
particles of a body when it is heated, "even their mean attraction &
repulsion can hardly be the same as if they w ere at rest in their mean
position." With a change in the arrangement and distance of the
particles, the size of the body changes. Although the observed
change is always an increase in the size of the heated body.
Cavendish could see no theoretical reason why it could not just as
well be a decrease.

J90

noted another experiment to try. In one plaee he
said that he wanted to determine if "friction is as
much diminished by oil & grease as the heat is"
(recall here one of Milner's objections to the
motion theory of heat). In another, he said that he
was concerned about the diminution of the latent
heat of a wire during an electric discharge. In
another, he said that he intended to expose various
equally dark bodies to sunlight to determine that
the total heat acquired by different bodies from the
sun's rays is the same. In the rough draft of "Heat"
he commented on this last experiment:

If it should prove that different bodies do not
receive the same total heat from the |sun|s light it
would be difficult to reconcile with this
hypothesis. But then it seems as difficult to
reconcile it with the supposition of heat being a
material substance except that as those hypotheses
are less capable of being brought to the test of
strict reasoning it is easier for those gentlemen to
find loop holes to escape by. 59

The experiments Cavendish planned all bore
on "this hypothesis," the fundamental, contested
hypothesis of Newton's theory of heat. His intention
is especially clear from another proposed experiment,
which appears in the discussion of the heat caused
by the impulse of light and Michell's experiment to
determine the momentum of sunlight: "Exper. to
determine the vis viva necessary to give a given in-
crease of sensible heat to a giv en body by alternately
exposing a thermometer in the (sun] & shading."''"

Whether or not Cavendish performed an
experiment like this, or any other experiments
with the same goal, we do not know. In any event,
the proposed experiment involved the calculation
of a mechanical equivalent of sensible heat for a
given substance.'' 1 Cavendish's interest in the
experiment did not end with this calculation. It
was the hypothesis of the theory of heat, the reality
of the vibrations constituting heat, that most
interested him, as he revealed in the rough draft of
"I Ieat," where he gav e a fuller statement of the
experiment. From the determination of the vis viva
equivalent to an increase of sensible heat in a body,
and by making a supposition about the variation of
the total heat in a body with its temperature, he
could "give a guess at the velocity with which the
particles of a body vibrate." 62

At the end of "Heat" Cavendish provided a
"Conclusion," which begins: "It has been shewn
therefore by as strict reasoning as can be expected

Cavendish

in subjects not purely mathematical, that if heat
consists in the vibrations of the particles of bodies,
the effects will be strikingly analogous, & as far as
our experiments yet go, in no case contradictory to
the phenomena." By showing that it is fully
sufficient to explain the phenomena. Cavendish
made a strong case for the hypothesis that the
vibrations of the particles of bodies constitute heat.
The hypothesis was not only sufficient, Cavendish
argued, but necessary. "To put the matter in a
stronger light," he said, it "seems certain that the
action of such rays of light as are absorbed by a
body must produce a motion & vibration of its
particles; so that it seems certain that the particles
of bodies must actually be in motion." Civen, then,
that the vibrations certainly exist, there must be
effects corresponding to them, and these are
"analogous to most of the phenomena of heat and
disagree with none." The hypothesis is demanded.'' 5
With these remarks Cavendish let rest the
case for Newton's theory of heat, having answered,
implicitly, the main criticisms of it. He showed that
the hypothetical vibrations can account not only for
the heat of friction, for example, for which a
motion theory would seem to be well suited, but
also for heats, such as those accompanying changes
of state, for which the material theory seems
especially well suited; the motion theory is a theory
for all of heat. In each application of the theory
Cavendish gave a picture of the motions and
configurations responsible, intended to show that,
unlike earlier motion theories, his theory could not
be faulted for lack of clear ideas of the mechanism.
By logical and, where possible, mathematical
arguments Cavendish proceeded from a precise
hypothesis and from accepted mechanical principles

"'Cavendish. "Heat," rough draft, 15. The experiment on
exposing dark bodies to sunlight is proposed in "Heat," 24.
"•Cavendish. "Heat." II.

'•'Distantly related determinations of the equivalence of heat
and work would be made systematically by others, using
experiments of different kinds, much later, in the nineteenth
century, when they would provide the foundation for the
development of the mechanical theory of heat.

'•-'Cavendish. "Heat," rough draft, 12. To make the calculation.
Cavendish would suppose "that the total heat of a body heated to
1,000 is double its heat at 0 ." It is easy to arrive at this supposition,
as we imagine Cavendish did, by assuming that the total heat of a
body is proportional to its specific heat and that the absolute zero of
temperature is -1,000' F, which is the order of magnitude of the
widely varying calculations of absolute zero made around this time.
Cavendish's goal was. and could be, no more than a "guess at the
velocity.".

"'Cavendish, "Heat," 40, 43.

Copy rig ht«t m aerial

Mercury

291

to a demonstration of the "striking" analogy between
the effects of invisible vibrations and the phenomena
of heat. He judged his theory to be a strong, good
theory, not "of that pliable nature as to be easily-
adapted to any appearances." 64

Cavendish was not finished yet. In the fair
copy of "Heat" he had not said a word about one of
its obvious motivations, the material theory, which
for Cavendish failed the criteria of a strong, good
theory. He reserved his judgment of the material
theory to the end of the "conclusion": given the
evidence for the existence of internal vibrations, he
wrote, there was no reason to "have recourse to the
hypothesis of a fluid, which nothing proves the
existence of." Moreover, not only was the material
theory superfluous, it was insufficiently testable
and therefore a weak theory:

The various hypotheses which have been formed
for explaining the phenomena of heat by a fluid
seem to shew that none of them are very
satisfactory; & though it does not seem impossible
that the fluid might exist endued with such
properties as to produce the effects of heat; yet
any hypothesis of such kind must be of that
unprecise nature, as not to admit of being reduced
to strict reasoning, so as to suffer one to examine
whether it will really explain the phenomena or
whether it will not rather be attended with
numberless inconsistencies & absurdities. So that
though it might be natural for philosophers to
adopt such an hypothesis when no better offend
itself; yet when a theory has been proposed by Sr
I.N. which, as may be shewn by strict reasoning,
must produce effects strongly analogous to those
observed to take place, & which seems no ways
inconsistent with any, there can no longer be any
reason for adhering to the former hypothesis. 65

Cavendish did not criticize the material theory in
general, nor any of its variants in particular, for
specific failures; he criticized it only for the kind of
theory it was. All material theories were burdened
with possible inconsistencies; all were weak by
comparison with the motion theory. The already-
tried hypotheses of the material theory were
unsatisfactory, but even if a hypothesis were found
that agreed with the facts, it would still be
unsatisfactory because it would be imprecise.

Three times in the conclusion of "Heat"
Cavendish used the expression "strict reasoning."
The phrase epitomizes the spirit in which
Cavendish studied physical nature. He had used it
before in his other great theoretical work: "The
method I propose to follow," he wrote in the

introduction of his published electrical theory of
1771, "is, first, to lay down the hypothesis; next, to
examine by strict mathematical reasoning, or at
least, as strict reasoning as the nature of the subject
will admit of, what consequences will flow from
thence"; and, finally, to compare these consequences
with experiment. 66 The method he used in the heat
theory was the same. It was to compare a
fundamental hypothesis about the nature of heat
with the results of experiment using mathematical
reasoning and, where that proved impossible, strict
verbal reasoning. His conclusion in "I leat" was that
Newton's theory of heat was the best theory because
of its high probability and its strict reasoning.

"Heat" carries no date, 67 but the pattern of
Cavendish's researches suggests that "Heat" was
not only later than "Remarks on the Theory of
Motion" but much later, falling in the late 1780s.
During the years 1783-88 Cavendish worked most
intently on heat and on the closely related subject
of pneumatic chemistry. With the exception of his
first publication, in 1766, all of his publications on
pneumatic chemistry appeared then, as did all of his
publications on heat. These experimental publica-
tions bore on the fundamentals of heat theory, as is

w Ibid., 41-42.
"Ibid., 42.

^Hcnry Cavendish, "An Attempt to Explain Some of the
Principal Phacnomena of Elcctricitv, by Means of an Elastic Fluid,"
PTM (1771): 584-677, on 584.

67 At recent sales it was assigned first to the decade 1795-1805
and then to around 1780, but both of these darings are probably off,
the truth lying somewhere in between. Cavendish certainly wrote
this paper after "Remarks on the Theory of Motion," which
mentions only some of the phenomena discussed in "Heat." Also, in
"Remarks" Cavendish regarded the cold produced by chemical
mixtures as a difficulty for the theory, whereas in "Heat" he no
longer did. Most important for this comparison is that in "Hear"
Cavendish drew on his knowledge of specific and latent heats and
developed the mechanical theory accordingly, whereas in "Remarks"
he did not mention them. The connection between "Heat" and
Cavendish's experiments on specific and latent heats is direct: e.g.,
the numbered paragraph 7 on p. 16 of "Heat," concerning the heats
of chemical mixtures, states in general terms the conclusion on p. 39
of the experimental notes on heat. Cavendish Mss 1 1 1 ( a >. 9. Christie's
sales catalogue assigned the first dating primarily on the basis of the
watermarks of the paper, in which the name J. Cripps alternates w ith
Britannia in a crowned circle. The assumption was that the earliest
recorded mark of James Cripps was in 1792. Cavendish did use the J.
Cripps stationery several times in the 1790s and 1800s. but he also
used it earlier, in the 1780s (the earliest appearance being manu-
script pages A3 through A5 of "Experiments on Air," Cavendish Mss
II, 10, published in the Philosophical Transactions in 1785). "Heat"
came up again at Dawsons of Pall Mall; James Cripps. father and son,
made paper from 1753 to 1803, it was noted, and based on references
to other authors in the manuscript, a dating of around 1780 was
proposed.

292

Cave it flith

shown by Cavendish's note on Newton's theory in
his 1 78.S publication.

As we have seen, in 1783 Cavendish
rejected Black's term "latent heat" because of the
theory' of heat it implied, and four years later, in
1787. he rejected another terminology for the same
kind of reason. The terminology proposed in the
Methode de nomenclature chimique implied Lavoisier's
theory of chemistry, and moreover it listed anions
the elements of chemistry the matter of heat,
"caloric." I pon receiving a copy of the treatise.
Cavendish wrote his "long sermon" to Blagden
about the "present rage of namemaking," which
sermon Cavendish took to heart when writing
"Heat." He now used the standard terminology of
mechanics, "vis viva" rather than his own
"mechanical momentum." By the same token, little
as he liked Black's terminology, he used it because
it was now standard. In his early writings on heat he
used expressions such as "heat is generated"; in
"Heat" he systematically used "latent heat," while
giving it an interpretation within the Newtonian
heat theory. "I leat" w as certainly w ritten after 1783.

That conclusion is firmed by Cavendish's
mention of other authors in "I leat." He cited
Joseph Priestley's book on the history of optics, but
that appeared early, in 1772. He cited the names,
but not the publications, of Scheele and Saussure
for their researches on radiant heat. Cavendish
closely followed Scheele's work — which, like his
own, joined the sciences of heat and pneumatic
chemistry — and the reference in "Heat" shows his
familiarity with Scheele's only book, w hich appeared
in English translation in 1780. 68 Cavendish's mention
of Saussure no doubt refers to the second volume
of his trav els in the Alps, which came out in 1786.'' 1 '
He cited no other authors in "Heat," and the
absence of citations to work done in the 1790s may
be taken as indirect evidence for an upper limit for
the dating. 70

For these several reasons we would place
"I leat" in or very close to 1 7<S7. As to the immediate
stimulus for writing the paper. Cavendish said
nothing. Researches on heat by others could have
provided it. In 1 785, for example, George Fordyce
published an experimental paper in the Philosophical
Transactions demonstrating the loss of weight by ice
upon melting. Since the ice lost weight as it gained
heat, he speculated that heat might be a body
possessing absolute levity. He was inclined to

believe that heat was a completely general quality
like attraction, only its opposite. Because any change
of w eight of a body w ith heat was thought to be an
argument against the motion theory, Fordyce's
experiments had a fundamental significance. 71 If
Fordyce's — and Crawford's too — were proven
right, Blagden told Laplace, they would work an
"extraordinary revolution in our ideas." 72 That was
recognized by Benjamin Thompson, who was later
to try to establish experimentally the motion theory
of heat. In 1787 Thompson repeated Fordyce's
experiments, convincing himself that they were
wrong and that heat could not be a material sub-
stance. 75 Cavendish had earlier witnessed experi-
ments like Fordyce's, and although he did none
himself and never discussed the question in print, 7 " 1
he was interested and was kept informed on
pertinent researches in Paris. 7 '' We do not believe,
however, that Fordyce's paper on heat or any other

'Mt is an indication of Cavendish's interest in Scheele's work
around the time of "I leat" that he. together w ith a helper, w rote out
a 24-page extract of Scheele's "New Observations on Air and l ire,
and the Generation of Water" from Crell's Chemische Annalen in 1 785:
Cavendish Mss X(c), 4. Cavendish wrote that Scheele "proved that
hot bodies emit not only rays of light, but also other particles, which
though not capable of exciting the sensation of light in our eyes are
yet able to produce heat. & which may therefore be called rays of
heat; he has shewn too that these rays of heat are reflected by
polished metals, but are neither reflected nor transmitted by glass":
Cavendish, "Heat." 23. Cavendish's source is undoubtedly the
experiments on "heat rays" and light using polished metal and glass
discussed in Carl W'ilhelm Scheele. Chemical Observations and
Experiments mi Mr and hire (1777). trans. J. R. Forster, w ith notes by
Richard Kirwan (London, 17X0). 72-74. 92-98.

'''Saussure. Cavendish said, "found that bodies emit rays of heat
though not near hot enough to emit rays of light": Cavendish, "I leat,"
23. Saussure described experiments he did with M. A. Pictet on the
reflection of "obscure heat" emitted by hot. but not red-hot. bodies
in Voyages dans Its Alps. vol. 2 (Geneva, I7W)). 354-55. Cavendish saw
this volume soon after it appeared; in a letter to Blagden, in response
to the latter's of Hi Sept. 1787, Cavendish wrote, "I do not know
whether you have seen the sequel of Saussures journey," and he-
gave some information from it: Cavendish, Set. I'up. 2:324—25.

'"For example. Pierre Prevost's experiments on heat rays and
Count Rumford's on the mechanical production of heat, belonging to
the 1790s. would have been relevant to Cav endish's argument .

"George Fordyce, "An Account of Some Experiments on the
Loss of W eight in Bodies on Being Melted or Heated." PT1S (1785):
361-65, on 364; Coleby. "Isaac Milner." 245.

"Charles Blagden to Lorenz Crell, 28 Apr. 1785, draft, Blagden
Letterbook, Yale. Charles Blagden to Pierre Simon Laplace, 5 Apr.
1785. ibid.

"'Sanborn C. Brown. Benjamin Thompson, Count Rumford
(Cambridge. Mass.: M.I.T. Press. 1979), 219-220. Fordyce himself in
1787 declared against the v iew that heat is a "substance." I Ie did not go
so far as to say that it is motion but called it a "quality": George Fordyce,
"An Account of an Experiment on I leat." / J '/'77 (1787): 310-17. on 316.

T4 John Roebuck. "Experiments on Ignited Bodies." PT 66
(1776): 509-12. These experiments, witnessed by Cavendish among
others, showed an increase of weight in iron and silver upon cooling,
a result in agreement with fordyce's later experiments.

Copy«ght«i maierial

Mercury

theoretical or experimental paper on heat around
17X7 was the occasion for Cavendish to write
"Heat." If it had been, he would have discussed it.
Nor, we believe, was the occasion any new
theoretical work of his own. "Heat" was not based
on a new understanding of his; the central idea, the
identification of heat with vis viva, had come to
him long before, at the time of the "Remarks." Nor
was the stimulus his own heat experiments, since
the experiments crucial to the refinement of the
theory, those on specific and latent heats, he had
done much earlier.

Another possible stimulus was the practical
applications of heat, which were abundant, the
time being the "industrial revolution." For several
years, in the mid-1 780s, Cavendish and Blagden
made journeys to various parts of Britain, visiting
industrial works wherever they went and making
close observations of power machinery, of water
wheels and steam engines, for example. The late
1780s were just the years of Cavendish's
concentrated researches on heat, including, if our
dating is right, the theoretical study "Heat." But
any stimulus Cavendish received from his
industrial tours was, at most, of a general nature.
"Heat" contains no practical discussions. On his
tours Cavendish took a keen interest in mechanical
forces in practice, but in "Heat" he treated the
subject philosophically. An example will bear this
out. To the text, immediately following his
calculation of the horsepower of light and his
proposed experiment to determine the vis viva
required to produce a given increase of sensible
heat in a body, he added this footnote:

If it was possible to make a wheel with float
boards like those of a water wheel which should
move with Vi the velocity of light without suffering
any resistance from friction cV the resistance of the
air, & as much of the [sun]s light as falls on a
surface of YA sq. feet was thrown on one side of
this wheel, it would actually do more work for any
mechanical purpose than 2 horses. 76

Implications for the conversion of forces for
practical purposes might be read into this, but the
example, taken at face value, is a thought experiment.

The principal reason why Cavendish wrote
"Heat," we believe, is that he had recently been
doing extensive experimental work on heat and
now wanted to clarify for himself, anew, the
theoretical foundations of the subject. His way of
clarification was by the systematic, rigorous

293

development of the consequences of the
fundamental hypothesis and the comparison of
these consequences with experimental results.
This interpretation is supported by two pages
among the unnumbered sheets at the end of the
rough draft of "Heat." These pages are evidently
notes Cavendish made before writing the draft, for
they list and briefly comment on the phenomena
he would discuss there. Some notes are
straightforward headings, such as "Heat from
action of [sun]s light" leading to the "calculation of
vis viva of [sun]s rays & of D° required to commun.
given quant heat." Other notes are tentative, as if
Cavendish were posing questions to answer. "I leat
by friction & hammering. Whether they can give
suffic. vis viva," to which Cavendish added a
footnote suggesting a possible answer to the
question: "Perhaps may where much force is
concentrated in small space as in boring holes etc
but as friction is not produced without tearing the
greatest part of heat produced thereby is likely to
be owing to other cause." To the note "Heat by
emission of light, the light commonly impelled by
repulsion of large particles of matter," he added a
footnote, "but quere whether this can be the case
in flame." He raised other questions. "Whether all
kinds of force applied should give any vis viva to a
body or only suffic. quick motions." "What is the
cause of friction & want of elasticity whether it is
not always owing to tearing off of particles or
altering their arrangement," which question was
followed up by a proposed experiment on friction.
"Cannot explain why the motion of the particles
should cause a body to expand," which is followed
by a suggestion about the altered interactions and
therefore positions of particles in motion. 77 There
is nothing in Cavendish's wording to suggest that
he was in any doubt about the truth of the
hypothesis that heat is the vibration of particles.
What it does strongly suggest is that he had
genuine questions about the explanations, based
on this hypothesis, of some principal phenomena
of heat. The working through of the theory' of heat
was an effort of understanding.

"Charles Blagden to Henry Cavendish, n.d.. /17K5/. Cavendish
MssX(b), 4.

"■Cavendish, "Heat," 11.

""Cavendish, "Heat." rough draft, two sequential, unnumbered
pages, the first beginning "heat from action of |sun|s light . . ."

294

Important as it was, Cavendish's need to
satisfy his own curiosity was, of course, not his only
motivation in writing "Heat." He was part of the
larger scientific world, and he was writing for it, in
intent if not in deed. He had much that he wanted
to say about the directions that that world was
taking. My the late 1780s, he saw the general
understanding of physical reality that had guided
his researches for twenty years everywhere under
attack or ignored. Cavendish's electrical theory was
regarded by his British colleagues as mathemati-
cally beyond them and remote from the experimental
problems they were addressing; abroad his theory-
remained all but unknown. 78 The late eighteenth
century was a time when electrical researchers
were commonly interested in the connections
between electricity and the ether, chemical action,
air, sound, light, and heat, whereas Cavendish's
theory was exclusively electrical, concerned solely
with the implications of a hypothetical electric
fluid together with the law of electric force. At the
same time, the old phlogiston theory of chemistry
was under attack. By 1783, when Cavendish
publicly defended the phlogiston theory, Lavoisier's
new understanding of combustion was well
advanced, and over the next few years chemists
began converting to it. By the time it was first
publicly taught in Britain, in 1787. the arguments
over the foundations of chemistry were running
decidedly in Lavoisier's favor. Pneumatic
chemistry, the science which owed greatly to
Cavendish's work, was just then acquiring a caloric
theory of gases, according to w hich the particles of
gases are surrounded by a repellent fiery matter.
Elsewhere, too. the New tonian theory of heat was
largely ignored, as we have seen: the number of its
remaining proponents was dwindling, while
writings on the material theory of heat were
growing. 7 '' The beleaguered Newtonian theory of
heat was a demonstrable physical truth to
Cavendish. It was supported by his researches not
only in the science of heat proper but also in the
two other sciences in w hich he had done his most
important work, chemistry and electricity. The
ether and the imponderable fluids were now
widely understood to have provided the basis of a
new, unified natural philosophy replacing the older
one subscribed to by Cavendish and a few other
British interpreters of Newton. Cavendish's goal
was to quantify the forces of attraction and

Cavendish

repulsion between the particles of matter, retaining
so far as possible Newton's unity of matter; it was
the program that Newton had laid down in query 31
of the Opticks. Cavendish demonstrated in "Heat"
that the older natural philosophy was not outmoded,
that it was more than adequate to the task of
accommodating recent experimental adv ances. These
considerations underlie the unusually forceful
wording of "Heat." This theoretical work conveys
a feeling of urgency that we find in no other
writing by Cavendish.

It is easier to understand the circumstances
of Cavendish's w riting "Heat" than to say why he
dropped it. First, it has to be remembered that
Cavendish did many original researches that he did
not see through publication. Yet he did publish his
most important researches, if only in part, so the
question remains why he apparently did no more
with "Heat." It is instructive to compare "Heat"
w ith Cav endish's manuscript "Thoughts Concerning
Electricity" and the mathematical propositions
belonging to it. Together they comprise thirty-five
manuscript pages, which is roughly the length of
"Heat." They are the preliminary version of the
long article containing a complete electrical theory
that Cavendish published in the Philosophical
transactions in 1771.*" He did not, so far as we
know, write the comparable, fuller version of the
theoretical work "Heat." Yet Cavendish might be
expected to have amplified and perfected "Heat"
for eventual publication in the Philosophical
Transactions, given the importance of the subject
for him and for science and given that "Heat,"
even as it stood, answered the main mechanical
objections to the motion theory.

'Tor example. Blagden. upon delivering to Cavendish a gift of
Rene-Just llaiiy's new treatise on electricity and magnetism, which
contained an electrical hypothesis similar to Cavendish's, observed
that the author seemed unaware of Cavendish's fundamental paper
of 1771: Blagden to C. L. Berthollet. draft. 11 Sept. 17X7. Blagden
Letterbook, Royal Society. 7:69. The reception of Cavendish's
electrical theory in light of contemporary directions of electrical
experimentation and speculation is discussed in McCormmach,
"Electrical Researches of I lenry Cavendish." 476-97.

'''In 17H6 Bryan Iliggins gave a "true calorie theory of gases" in
his Experiments duel Observations Relating to Acetous Acid; Fox, Caloric
Theory, 11,21, ZZ.

""Henry Cavendish. " Thoughts Concerning Electricity" and
"Cavendish's First Mathematical Theory." Cavendish Mss I, 17 and
is. and his published paper of 1771. "An Attempt to Explain Some
of the Principal I'haenomena of Electricity, by Means of an Elastic
Fluid," reprinted in I'/ie Electrical Researches of the Honourable Henry
Cavendish, ed. J. C. Maxwell (Cambridge: Cambridge University
Press. 1S79), 94-103, 411-17. and I-6.V respectively.

Mercury

295

Blagden, in advising Lord George about
Cavendish's unpublished papers, said that
Cavendish was "always ready to publish" what was
good. Moreover, Cavendish was acutely aware that
if good work is withheld, it will likely be forestalled
by someone else.* 1 This unhappy outcome,
however, was not likely in the case of "Heat," nor
was rivalry with its disagreeable consequences. No
one had come forward with a work like
Cavendish's, nor would anyone soon. The paper
would draw criticism, but Cavendish knew that
when he wrote it.

A possible reason for abandoning work on
the theory is the new experiments that occurred to
Cavendish in the writing of "Heat," but we doubt
that they have any bearing on the question. He did
not need more experimental proof: he was, he said,
as fully convinced of the theory of heat as he was of
anything in science this side of pure mathematics.
In a footnote in "Heat" he referred to the "text,"
and he drafted the whole twice and planned yet
another writing in which certain paragraphs would
be reordered. There can be little doubt that it was
with publication in mind that Cavendish wrote the
preliminary drafts of "Heat."

It may be that when Cavendish began
"Heat" he expected more from it. Founded on the
principles of mechanics, Cavendish's theory of heat
was mathematically rigorous, but at the stage he left
it, with the manuscript "Heat," he had not yet
shown it capable of predicting new, quantitatively
determinable phenomena. In that important respect
its development was inferior to that of his electrical
theory, which had impressive predictive powers.

Referring to Cavendish's papers that went
unpublished, Blagden said that "it is to be
supposed that he afterwards discovered some
weakness or imperfection in them." But if the
ideas in "Heat" were not good enough for
Cavendish, given his standards, the question is
only pushed back. What were his standards and
what was their source? "When a theory has been
proposed by Sr I.N." and agrees with the facts,
Cavendish said of Newton's theory of heat, it is to
be accepted. Cavendish spoke of "Newton's"
theory; and though in reality it was his own theory;
to his way of thinking they were one and the same.
Cavendish had written up his electrical researches
as an intended treatise on the universal force of
electricity, an electrical system of the world, in

form and substance the electrical sequel of
Newton's universal gravitational system of the
world. Heat was an equally fundamental subject,
its phenomena even more universal than those of
electricity and gravitation, since heat is produced
by every kind of force. Its proper treatment would
have required yet another treatise, another chapter
in the final treatise on the one, encompassing
system of the world of particles and forces. It is
against the standards established by Newton that
Cavendish's individual mix of assertion and caution
must be viewed.

The Natural Philosopher

In The Life of the Honourable Henry Cavendish,
George Wilson defined Cavendish's universe as
consisting "solely of a multitude of objects which
could be weighed, numbered, and measured."
Wilson came to this understanding of what he
called Cavendish's "Theory of the Universe" after
examining his chemical papers closely and his
papers on heat cursorily. These papers contained
experimental researches in which weighings,
thermometer readings, and like numbers occurred
throughout. They were, Wilson believed, the
restricted language of a man whose elected
vocation was to "weigh, number, and measure as
many of those objects as his allotted three-score
years and ten would permit." A "calculating
engine" was Wilson's characterization of Cavendish.* 2
Wilson's judgment has been uncritically repeated
ever since, but he was fundamentally in error about
his subject.

In all three of Cavendish's major original
lines of research, chemistry, electricity, and heat, he
did a series of experiments after he had sketched
out the basic theory. Cavendish's chemical
researches were guided by the phlogiston theory,
which he discussed in his earliest, unpublished
chemical writings and more fully in his published
ones. The starting point of his electrical researches
was the unpublished "Thoughts Concerning
Electricity" and their elaboration and refinement
in the published theoretical paper of 1771.
Cavendish's researches in heat, as we have seen,
began in an unpublished paper on mechanics.

"Cavendish to Miehell, 27 May 178.V
"-'Wilson. Caimirlish. 185-86.

296

"Remarks on the Theory of Motion." All of these
earliest theoretical writings belong to the 1760s,
w hen Cavendish w as in his thirties and just setting
out as a researcher. For the rest of his life he
worked from these theoretical ideas, modifying
them as needed, perfecting them, and studying the
phenomena in question experimentally.

Cavendish's goal was the understanding of
nature, not calculation for its own sake. That much
is clear from "I leat," though the manuscript contains
calculations. Following the mechanical theorems
governing vibrating particles, Cavendish carried
through a long calculation for the example of electric
discharge and another for Michell's experiment.
But for the most part the subject of heat did not
yet lend itself to extended mathematical and
quantitative treatment. The persuasiveness of
Cavendish's paper derived from another source, its
coherence, comprehensiveness, and strict reasoning,
which included mathematical reasoning where it
applied. Passing from one branch of natural
philosophy to another, he argued that the
phenomena were explained by Newton's theory.
From beginning to end, "Heat" gave testimony
that heat consists of the invisible vibrations of
bodies; it gave understanding.

In developing his case for Newton's theory,
which is a theory about nature at the level of the
particles of matter. Cavendish repeatedly called on
a general standpoint. Elsewhere in his writings he
called on it, too, but only in "Heat" did he make
explicit his fundamental beliefs about the ultimate
constituents, his " Theory of the Universe." 'The
discussion occurs in a footnote to the discussion of
friction, which in the rough draft is motivated by
an observation omitted from the fair copy: " The
nature of friction & imperfect elasticity deserves
to be considered more accurately." The fair copy
continues:

According to l ather Boscovich & Mr. Michcll
matter does not consist of solid impenetrable
particles as commonly supposed, but only of
certain degrees of attraction Cv repulsion directed
towards central points. They also suppose that the
action of 1 of these central points on each other
alternately varies from repulsion to attraction
numberless times as the distance increases. There
is the utmost reason to think that both these
suppositions are true; <Sc they serv e to account for
many phenomena of nature which would
otherwise be inexplicable, but even if it is
otherw ise, & if it must be admitted that there are

Cavendish

solid impenetrable particles, still there seems
sufficient reason to think that those particles do
not touch each other, but are kept from ever
coming in contact by their repulsive force. 83

This is what Cavendish thought the world was
made of. He believed that Boscovich and Michcll
were likely to be right about particles, but it would
change nothing if Newton was right. In either case,
the force of repulsion keeps particles from
touching and losing vis viva, which is the point/ 4

John Michell's views were made public
through Priestley's account of them in 1772 in his
history of optics. HS Roger Joseph Boscovich's were
known directly, principally through his treatise
Theoria philosophiae t/afura/is, w hich appeared just
as Cav endish was setting out as a researcher. 86 The
Leibnizian and Newtonian elements in Boscov ich's
theory, such as Leibniz's law of continuity and
Newton's attractive and repulsive forces, made his
theory compatible with, and useful for under-
standing, Newton's theory of heat in the form
Cav endish gave to it. In Boscovich's world of point
masses interacting through central forces, there
could be no friction or inelastic collisions, which
destroy vis viva. At close separations, particles
experience infinite repulsion, at large separations
gtav national attraction, and in between the
attractions and repulsions responsible for cohesion,
v aporization, and a great variety of other chemical
and physical phenomena. Boscovich represented
his universal "law of forces" by a continuous curve:
above the axis the force is repulsive, and below it

si Cavendish, "Heat." rough draft. 17-18; and Cavendish.
"Heat." 28-2^. Cavendish's questioning of the existence of solid,
impenetrable particles in the context of a conservation law belongs
to a Ions debate, which is the subject of Wilson I.. Scott. The Conflict
between Atomism and Conservation theory, I644-IX(>0 (New York:
Elsevier, 1970).

M With this statement by Cavendish, a puzzle is solved. In a
number of places in his writings he spoke of particles as if he thought
of them as New tonian solid bodies, w hile in other places he spoke of
them as if he did not. In "Heat" he explained that either view was
acceptable to him.

" 5 Priestley, History 1:392-93, 311. Priestley not only gave
Michell's views on matter and forces but also his application of them
to Newton's observations of the colors of thin plates and to the
immense force with which light is emitted from bodies: ibid..
309-11, 392-93, 786-91. In his electrical researches Cavendish used
Michell's explanation of colored plates as an analogy for the motion
of electricity w ithin ulass plates: "Further Experiments on Charges
of Plates. . Cavendish Mss 111(a). S; Set. Pap. 2:354-62. on 361-62.

" Priestley also discussed boscov ich's v iews in his History, but
( lavendish had not them directly from their author in his first edition
of 1758 of the Theoria. We note too that Cav endish and Michcll met
Boscovich on his tour of England, both dining with him at the Royal
Society Club on 5 June 1760 and Cavendish with hint again on 26
June 1760: Royal Society Club Minute Book. Royal Society.

Copynghted

Mercury

>>)7

attractive, and the points where it passes from
repulsion to attraction mark limit points of
cohesion. Particles vibrate about these points when
disturbed, and the vibrations continue indefinitely
until the particles are again disturbed. The area
between the curve and the axis is proportional to
vis viva, since it measures the action of a force-
across a distance. Boscovich's theory, with its
implied possibility of perpetually vibrating particles
accounting for combustion, dissolution, and fer-
mentation, and with its implied conservation law,
provided support for Newton's theory of heat,
which is why Cavendish introduced it in "Heat." s7

Cavendish, as we know, accepted as the
first task of natural philosophy the determination
of forces, but the forces responsible for the
phenomena of heat act over minute distances and
are otherwise inaccessible. It is problematic that
they can be known in the way that gravitation is
known, in detail, in the form of a mathematical
law. xs Nevertheless, as Cavendish showed, the
phenomena of heat can be deduced from a
knowledge only of the general nature of the acting
forces. Boscovich's law of forces encompasses
forces that depend on the distance and are directed
to central points, and so these forces satisfy the
assumptions of Cavendish's derivation of the
conservation law. It is conceivable that Cavendish's
reading of Boscovich gave him his original direc-
tion, but for someone as widely read as Cavendish
we doubt that the impetus was so straightforward. 84
It is clear that early on, Cavendish mastered
Newton's science, but he needed more than Newton
could give him to develop "Newton's" theory of
heat, and important as Leibnizian vis viva was for
Cavendish's purposes, that did not give it to him
either. Neither did Michell's and Boscovich's views
on the nature of matter and force. Rather Caven-
dish drew on all of these sources and on his and
others' experimental investigations of heat, and by
strict reasoning, he brought them together to make
the theory he presented in "Heat."

Cavendish was not one to speculate on the
unity of nature. He developed mathematical
theories and followed them with experimental
measurements, carefully delimiting the phenom-
ena under review. For work of this kind it was
important to make distinctions, not assert unities.
Yet he held to a theoretical view by which the
disparate phenomena of nature are seen to have a
uniform cause in attractive and repulsive, centrally
acting forces. 90 This understanding, together with
the mechanical theorems about vis viva, permitted
Cavendish to display a connectedness, through an
analogy with heat, between the several major
domains of delimited phenomena constituting the
broad field of natural philosophy.

" ; lt makes no difference here that Boscovich himself believed in
the matter of fire: Roger Joseph Boscovich, .1 Theory of Natural
Philosophy, trans J. M. Child from the 2d edition of 1763 (Cambridge,
Mass.: MIT Press, 1966), ZZ-Z)>. 43, 7.5, 76-96. Boscovich did not
have a conservation law and generally regarded vis vka as having
little significance; it may be surprising given his theory's ready
explanation of the conservation of vis viva. Thomas I.. Nankins,
"Kightcenth-Century Attempts to Resolve the Vis viva Controversy,"
/sis 56 (1965): 281-97, on 294, and on Boscovich, 291-97: on Michell
and Boscovich, Schofield, Mechanism and Materialism, 236—49.

""To the time of Cavendish's "Heat." the search for the laws of
the forces acting over minute distances had proven unsuccessful.
The law of force of light particles eluded Newton's followers as it
had Newton, and no "universal synthesis of short-range forces" had
been established: Cantor. Optics after Newton, 87. There was a way of
retaining, in part. Newton's understanding of the future of natural
philosophy: it was not to wait until the laws of force were know n but
to "compute the forces" in ignorance of them, using vis vka. I hat
was Cavendish's way. one suggested by Boscovich's law of forces.

"'Michell arrived independently at views similar to Boscovich's,
and Cavendish may have done so. too. given the theoretical
problems he was working on. It has been pointed out that there was
a British tradition paralleling Boscovich's views; ibid., 71-72;
Schofield, Mechanism and Materialism. 237-38; and I'. M. Ileimann
and J. E. McGuirc, "Newtonian forces and Lockean Powers:
Concepts of Matter in Eighteenth-Century Thought." Historical
Studies in the Physical Sciences 3 ( 1971 ): 233-306.

"'In view of the incompleteness of Cavendish's manuscripts, it
is hazardous to speak confidently of what he did not
accomplish, That has been done by Vukitoshi Matsuo, who asserts
Cavendish's "failure to unify a variety of heat phenomena in terms of
dvnamics and his subsequent abandonment of a systematic
consideration of them." Equally hazardous is his consequent
assertion that Cavendish never "gave any special consideration to
systematic thought in chemistry": Vukitoshi Matsuo. "Henry
Cavendish: A Scientist in the Age of the Revolution chimique, "
Japanese Studies in the History of Science 14(1975): K3-94, on 93-94.

CHAPTER 5

Jky

The astronomical observations that Henry
Cavendish made with his father probably gave him
his start in science. He went on to do work on
nearly every astronomical subject: instruments,
atmospheric refraction, tides, earth, moon, planets,
comets, sun, and stars. His astronomical papers
constitute the largest single group of manuscripts.
These papers, part observational and larger part
mathematical and theoretical, often begin as
carefully drafted studies with a clear objective and
then trail off into calculations of unclear significance,
but in a number of instances they have a finished
quality and are meant to be shown to someone.
Although he did not single out any one central
problem in astronomy, here as in other areas of
science, he took a painstaking interest in instru-
ments and in methods and errors of observation. He
did not make systematic observations of the heavens
like Nevil Maskelyne or William Herschel — he did
not have that kind of observatory and he did not
spend his life that way — but he made observations
from time to time to test techniques, such as taking
transits, and he looked at things that other
astronomers were looking at, a planet, a comet, a
variable star, or volcanoes on the moon. 1

In the v icinity of London there was a series
of observatories roughly following the course of the
Thames. Cavendish's observatory at Clapham Com-
mon was directly south of London, and on a line with
it to the east were Aubert's observatory at Loam Pit
and just beyond that the Royal Observatory at Green-
wich, where Maskelyne worked. Considerably to
the west of this group was Herschel's observatory
near Windsor Castle. From 1788 Aubert had a new
observatory, built for him by Smeaton at Islington,
directly north of London. 2 The astronomers were
in the practice of paying visits to one another's obser-
vaiorics* and to collaborating, as we show by example.

Collaborators

The 1780s were a time of discovery in
astronomy, and the greatest discoverer was William

Herschel. He was the first person known to have
discovered a new major planet, in 1782, which he
astutely named after George III (it was renamed
Uranus), who rewarded him with a royal pension,
freeing him from his original profession, music.
Herschel settled near Windsor Castle, where he
spent the rest of his life making observations at
night and, by day, telescopes, which he either sold
to supplement his pension or used himself to see
ever deeper into space. In 1783 he began his
systematic "sweeps" of the sky, and at the same time
he worked on a telescope of (for that time) gigantic-
proportions, four feet across and forty feet in length.
Blagden walked through the iron tube of this tele-
scope hardly having to stoop. 4 Herschel never got
this telescope to work satisfactorily, but its size was
a proper measure of his ambition, which was to see
to the ends of the universe and to determine the
configuration of all of its contents. In these years
he made his single most important contribution,
his theory of the structure of the visible universe
based on a great mass of observ ations he had made. 5
His addition to astronomical knowledge was prodi-
gious. This imaginative and industrious observer

'Herschel observed what he regarded as an eruption on the
moon, shining with a fiery light, and he observed two "extinct"
volcanos as well, concluding they were volcanos "by analogy, or with
the eye of reason." William Herschel, "An Account of Three
Volcanos in the Moon," PT 77 (1787): 229-32. quotation on 229. To
see Herschel's volcanos. Cavendish and Blagden used a very good
achromatic telescope, owned by Cavendish. With it they saw the
unusual light in the dark part of the moon's surface w here Herschel
had located the big volcano. Charles Blagden to Mrs. Grey, 14 June
1787, draft, Blagden Letterbook, Royal Society, 7:324.

- These observatories were all used as corners of triangles in the
great trigonometrical operation of the 1780s. They are show n in the
plates at the end of W illiam Roy, "An Account of the Trigonometrical
Operation. Whereby the Distance Between the Meridians of the
Roval Observ atories of Greenw ich and Paris 1 las Been Determined."
/T80O790): 111-270.

■'For instance, Aubert planned a dinner at Loam Pit for
Cavendish. Herschel, Michell, Smeaton, Blagden. and Lord
Palmerston. Alexander Aubert to William Herschel, IV June 1786,
Royal Astronomical Society, I lerschel Wl/13, A3.

••Charles Blagden to John Michell, 31 Oct. 1786, draft, Blagden
Letterbook, Royal Society, 7:49.

5 Michael A. Hoskin. William Herschel inul the Construction of the
Hem-ens (New York: American Elsevier, 1963). 17-18, 62-64.

300

lived near Cavendish, who naturally took the greatest
interest in his work.

As a guest of the Royal Society Club one
day, John Playfair noticed that the members paid
no attention to their guests, w ho included several
foreigners. There was one exception, Alexander
Aubert, whom Playfair found "a very polite man,
and a great consolation to a stranger."'' This detail
captures a truth about Aubert: he was observant
and helpful. Aubert seemed to have had no
personal ambition in astronomy but only a passion
for it and a standard of excellence. Equipping his
observatories with instruments by the leading
instrument-makers, Jesse Ramsden, Peter Holland,
John Bird, and James Short, he was reputed to have
the best astronomical establishment of any private
person in the country. 7 Because of the quality of his
instruments, Herschel appealed to Aubert to
confirm his ow n observations so that they would be-
taken seriously.* Wealthy (needless to say), Aubert
w as a director and from 1 7S7 gov ernor of the London
Assurance Company. He brought his administrative
skills to his learned side pursuits. A Fellow of the
Royal Society since 1772, he was elected to the
council and appointed to committees for astronomy
and meteorology, on which he served regularly
w ith, and almost as often as. Cavendish. When John
Pringle stepped down as president of the Royal
Society in 1778, the council considered two members
to replace him, Aubert and Banks, and after long
deliberation they made their fateful choice of
Banks. 1 ' In the Society of Antiquaries, Aubert serv ed
as vice-president. I le combined an observ ant nature
with a daring streak: as chairman of the Harbour
Board, he descended to the bottom of Ramsgate
Harbour in a diving bell to examine a pier." 1 His
avoidance of controversy was made easier by his
avoidance of publication. 1 1 I le and Cavendish were
the same age and had similar interests, and they
saw each other constantly at their clubs. As he did
in the case of Blagden and Dalrymple, Cavendish
brought Aubert into his financial affairs as a trustee
of his property at Clapham Common. 12

Cavendish saw Maskelyne as often and in
the same places, at the Royal Society and at their
clubs. Maskelyne brought to Cavendish something
that I lerschel and Aubert did not; he was not only
a man of observation and instruments but, like
Cavendish, he was a mathematician as well, and the
memoranda that passed between Maskelvne and

Cavendish

Cavendish reflected that uncommon ability. Like
Herschel, Maskelyne was hard working and prolific,
but there the resemblance ends. Maskelyne did not
engage in Herschel's flights of theorizing, which in
any case would not have been invited by his
position at Greenwich, but it was not in his nature
to do so either. Playfair made an apt observation:
Maskelyne "is slow in apprehending new truths, but
his mind takes a very firm hold of them at last." 1 * 1
Maskelyne could be defensive and short- tempered,
and he could even be rude to Cavendish, 14 but his
methodic exactness and his devotion to astronomv
suited Cavendish, and their two difficult tem-
peraments were compatible.

Remote from his colleagues in London,
from his home at Thomhill, Yorkshire, John
Michell kept up an astronomical exchange as best
he could. Of what sort of observatory he had, if any,
there is no record, but of his intentions we know a
good deal. Michell would have liked to succeed
James Bradley as astronomer royal, but he did not
have the connections or, it would seem, proof of
observational competence. 15 Also standing in his
w ay of high ambition was MichelPs behav ior as an
independent whig at Cambridge, offending the
influential John Pringle, for example."' Throughout

6 Playfair quoted in Archibald Gcikie, Annuls of the Royal Society
Club (London: Macmillan, 1917), 160.
7 "Aubert. Alexander." 1:715.

"William 1 lerschel to Alexander Aubert, 9 Jan. 17K2, copy, Royal
Astronomical Society. Herschel W'I/1, pp. 21-24; published in
Constance A Lubbock, The Herschel Chronicle. The Life-Story of
William Herschel and His Sister Caroline Herschel (( )ambridgc: ( lambridge
University Press. 1933), 102-3.

'Henry Lyons. The Roynl Society. 1660-1940: A History of Its
Administration under Its ( barters (New York: Greenwood, 1968). 197.

"'Bernard Drew, The London Assurance, a Second Chronicle
(London: printed for The London Assurance at the Curwen Press.
Plaistow, 1949). 159.

"Aubert published very little diirinn his long activity in astronomy:
there were some observations of the transit of Venus in 1769. a new
method of finding time by equal altitudes in 1776, and an account of
meteors in 1783, all appearing in the Philosophical Transactions.

'-'In a bundle of papers concerning Cavendish's Clapham
Common property are extracts from Aubert 's and Aubert 's heirs'
wills. These materials were assembled to transfer the property to the
duke of Devonshire after Cavendish's death. Devon. Coll., L/38/78.

''John Playfair, The Works of John Playfair, cd. J. (i. Playfair, 4
vols. (Kdinburgh, 1X22). 1: "Appendix." no. I: "Journal." Ixxviii.

l4 Charles Blagden to Joseph Banks. 16 Oct. 1 7X3. I'it/w illiam
Museum Library, Pcrcival 11190.

"Thomas Birch to Philip Yorke, 17 July 1762. BL Add Mss
35399, ff. 298-301.

"'Alexander Small to Benjamin franklin, I Dec. 1764. Papers of
Benjamin Franklin, cd. L. W. Labaree, vol. 11 (New Haven: Vale
University Press. 1967). 479-83. Also involved in the politics of this
appointment to astronomer royal was Michell's vote on John
Harrison's chronometer, for voting against it. Michell further

Siy

301

the 1780s Michel! worked on a reflecting telescope
that was second only to Herschel's. Its main mirror
was two and a half feet across, ground, polished
(and broken) by Michell, and acquired by Hcrschel
after Michell's death. 17 We do not know what
Michell planned to do with his telescope once he
had perfected it, for his publications in astronomy
were — by default, it would seem — theoretical. In
speculative verve he was Herschel's equal, and
since he had mathematical skills equal to
Maskelyne's and Cavendish's, he could develop his
theoretical ideas farther. In breadth of scientific
knowledge, Michell resembled William Watson,
who was now near the end of his life: like Watson,
Michell was knowledgeable in natural history as
well as in natural philosophy. Michell lived in the
vicinity of Priestley, allowing visits; the two did not
regularlv correspond, and'* Michell wrote only one
letter to Herschel. 1 '' For his personal contact with
men of science, Michell regularly made the long
journey from Yorkshire to London. An historian
notes that for the English middle class in the
eighteenth century, travel "was too irksome or
expensive for most to pay more than one or two
visits to the great world of London, and such visits
rarely repaid them." 20 That could not be said of
Michell. His one sustained correspondence with
Cavendish was a continuation of a conversation on
astronomy from his last visit to London. This
exchange had ramifications, as we will see.

Weighing the Stars

Newton wrote in the Pritiapia that all
bodies are to be regarded as subject to the principle
of gravitation. 21 Insofar as ordinary matter was
concerned (excluding the imponderable fluids), this
postulated universality of mutual attraction was, for
followers of Newton, an untested article of faith for
nearly a century. During this time the evidence for
attraction continued to be drawn from the motions
of the earth, moon, planets, comets, and falling
bodies, and recently from the attraction of
mountains, phenomena which span an intermediate
range of masses, sizes, and distances. In three
domains of experience, involving the greatest and
the smallest bodies, the action of gravity had not
yet been observed: the gravity of the "fixed" stars;
the mutual attraction of hand-held sized bodies;
and the gravitation of the particles of light. The
task of deducing observable consequences from

each of these supposed instances of universal
gravitation fell to Michell, and his friend Cavendish
encouraged him in these researches and became
involved in the resulting observational and experi-
mental questions.

Michell and Cavendish received a body of
opinions on the nature of stars, which included the
understanding that stars shine by their own and not
by reflected light, and that their light and the sun's
are of the same kind. It was understood that stars
are physical bodies, suns, each with its gravita-
tionally bound family of planets and comets, each
supplying its world with warmth and light and life.
Stars were known to be immensely distant from
earth and from one another, which explained why
their planets were invisible.

The exact distance of the stars was the great
problem of the astronomy of stars. From expeditions,
astronomers had determined the earth's measures
and the measures of the solar system — the
worldwide observations the transits of Venus had
been directed to this end — but the measures of the
stellar universe remained unknown. Lord Charles
Cavendish, as we have noted, got his start as a
practicing scientist by helping Bradley look for the
distance of the stars. Henry Cavendish carried on
the search, as we will see, working with astronomers
Herschel and Michell as they looked for the same
thing by other means.

Bradley's failure to detect any parallax had
led him to remove the stars to a distance of at least
40(),()()() times that of the sun; this lower bound on
stellar distances was cited often through the
century. Hcrschel made surveys of double stars
with the hope of finding the parallax by a well-

offended Pringle. James Short, who also was in the running tor the
job. voted the other way on Harrison, thereby offending another
influential person, Lord Morton. Ibid.

,7 Hcnrv C. King. History of the Telescope (Cambridge. Mass: Sky
Publisher, 1955), 91.

'"Joseph Priestley to William Herschel, 12 Aug. 17K0. in Joseph
1'riestlev, .1 Scientifu Autobiography of Joseph Priestley (1733-1804), ed.
R. E. Schofield (Cambridge, Mass: M.I.T. Press, 1966), 1X6.

i»John Michell to William Herschel. 12 Apr. 17H1, in William
Herschel. The Scientific I'ttpers of Sir William Herschel. ed. J. I.. K.
Drcycr. 2 vols. (London: The Royal Society and the Royal
Astronomical Society. 1912) l:xxxii.

a, Basil Williams. The Whig Supremacy. 1714-1760. 2d rev. ed., ed.
C. II. Stuart (Oxford: Clarendon Press, 1962). 144.

-'' The following discussion is taken from Russell McCormmach,
"John Michell and Henry Cavendish: Weighing the Stars." British
Journal (or the History of Science 4 (1968): 126-55. For material used
from that article, we acknowledge permission by the Council of the
British Society for the I listory of Science.

302

known indirect method. If two stars that looked
close were actually at very different distances and
w ere only lined up with the earth, the fainter of the
two stars could be considered sufficiently distant as
to be fixed, and the apparent displacement of the
brighter star as viewed from the orbit of the earth
could be measured with reference to it.

1 Ierschel's method of finding the distances
of stars was useless, of course, if nearby stars were
actually neighboring ones. Michell had reason to
believe that they were often indeed neighbors: in
his two major papers on astronomy, in 1767 and
1784, he regarded close-lying stars as clusters, their
members removed the same distance from the
earth. In the first of his papers, he made an original
application of the doctrine of chances to astronomy,
arguing that the great number of observ ed nearby
stars could not be the result of accident. He
assumed that most stars that looked close were
physically bound by mutual gravitation, Civen
certain hypothetical data, the distances and sizes of
these companion stars could be estimated on
photometric principles.-- Not convinced by Michell's
probabilistic reasoning, as he later would be by
observational evidence that most double stars were
companions, in 1 782 I Ierschel published a great
catalogue containing 269 double stars, most of
which he had discovered himself.- 5 It was this
publication of I Ierschel that prompted Michell to
write his second paper dealing with double stars.
Michell had had no idea that there were so many of
them. Kncouraged by the observational possibilities,
he proposed a new method of determining the
measures of stars, their distances, sizes, and w eights.
I le sent a paper on the subject to Cavendish to
communicate to the Royal Society, accompanied
by two letters, one to introduce the paper, and the
other to remind Cavendish of the conversation
they had on the subject and to say that no one else
was as suited as he to judge the paper.-' 4

Michell's method depended upon the
assumption that the light emitted by stars was
attracted back to them. The gravitational motions
of the particles of light were not ordinarily
observed because of their great velocity, but still,
Michell reasoned, an extraordinarily massive body
such as a star might attract its own light with
sufficient strength to cause a measurable reduction
in its velocity. Michell, in fact, had calculated the
gravitational retardation of the sun's light for

Cavendish

Priestley's History of Optics in 1772, and he followed
this line of reasoning in the paper he sent
Cavendish in 1783.-' s

Michell calculated that if a star of the same
density as the sun had a radius 497 times greater
than the sun's, it would attract back to itself all of
the light it emitted; thus, at great distances it
would be invisible, though its existence might be
inferred by a visible star rotating about it. The light
from a smaller star would continue to infinity
though with a retarded velocity, and it was this
retardation that Michell hoped to detect. Based
upon Newton's view that the faster light travels,
the less it is turned from its course by a refracting
medium like glass, Michell's plan was to point a
narrow-angled prism at a double star with the
leading edge of the prism at right angles to the line
joining the stars. The observer would then rotate
the prism, directing the light from the stars first at
one face and then at the other. Because the
retarded light from the central star would be
refracted more than the light from the smaller star
rotating around it, the pair would be seen to have a
slightly different angular separation in the two
prism positions. The difference was necessarily
small, but Michell thought that John Holland's
achromatic prisms could reveal it if the central star
were, say, of the sun's density and at least twenty-
two times its size.-''

To draw conclusions about the distance,
size, and weight of a central star from the change in
the refrangibility of its light, it was necessary also to
know its angular diameter and the period of the
star revolving around it. Neither was known for anv
stars, but Michell thought that it was not out of the
question that this information could be found for

--John Michell, "An Inquiry into the Probable Parallax, and
Magnitude of the Fixed Stars, from the O'luntity of Light W hich
They Afford I's, and the Particular Circumstances of Their
Situation," PT 57 (1767): 234-64.

-'William Herschel. "Catalogue of Double Stars," I'Tll (1782):
112-62.

- 4 John Michell to Henry Cavendish, 26 May 1783, Cavendish
Mss. New Correspondence. Michell's paper was published, "On the
Means of Discovering the Distance, Magnitude, etc. of the Fixed
Stars, in Consequence of the Diminution of the Velocity of Their
Light, in Case Such a Diminution Should He Found to 'Take Place in
Any of Them, and Such Other Data Should Be Procured from
Observations, as Would Be Farther Necessary for 'That Purpose," Pi'
74(1784): 35-57.

"Joseph Priestley. The History and Present Suite of Discoveries
Rehiring to Vision. Light, imel Colours (London, 1 772). 787-91 .

-'■Michell. "On the Means of Discovering the Distance." 51, 53.

M.I

some stars somewhere in the "infinite variety" of
ereation, though it might take "many years, or
perhaps some ages." 27 Whatever the future held for
attempts to observe the dimensions and motions of
double stars, the method stood or fell by the
measurement of the decrease in the speed of the
light from the stars. This measurement could be
made independently of observations of stellar
diameters and motions and might succeed
immediately, a prospect which drew the attention
of astronomers in London, who wanted to try the
measurement as a fundamental experiment. If it
worked, they had in mind an application that did
not have to be deferred for years or ages. If the
solar system had a preferred direction in space, the
light coming from stars in that direction would, by
a simple addition of velocities, strike the earth with
greater speed than would the light coming from
the opposite direction of the sky. 2K Michell's
method could measure the speed with which the
solar system was moving toward or away from
given stars. (In 1783, using another method,
Herschel concluded that the solar system was
"moving very fast," Cavendish wrote to Michell. "I
forget the direction." 29 )

Michell's proposal fell on prepared ground
for another reason. In London the year before, and
earlier in Paris, there had been much discussion of
a scheme for deciding if light really does move, as
Newton said it did, with greater velocity in a more
refracting medium. Patrick Wilson, assistant to
Alexander Wilson, professor of practical astronomy
at Glasgow University, proposed an experiment
using a telescope filled with water. If the predic-
tion was confirmed, he said, it would be "very
strong additional evidence" for Newton's optical
principles. 511 There was a small dispute over the
priority of this discovery, and when it came up at a
dinner of the Royal Society Club, "Mr Cavendish
put in, that he did not think it a matter of any
consequence to either of them, as nothing seemed
likely to be determined by that method." 51

Michell's method was another matter. Upon
receiving Michell's paper, Cavendish wrote that he
was "glad you put your thoughts on this subject
upon paper." 32 He pointed out a mathematical slip,
and he came to disagree with Michell on the best
apparatus for detecting the retarded light, but he
did not criticize the basic idea of the paper. That
the matter of the stars should exert a gravitational

pull upon the particles of light and affect their
velocity was for him a correct physical assumption. 35
It was not for everyone. 54

Michell asked Cavendish to communicate
his paper, but if that could not be done before the
recess, he wanted Cavendish "not to let the
principle of it go abroad, till the paper itself can
come before the Society, for reasons, that will be
sufficiently obvious." 55 If the reasons were obvious

-''Michell, "On the Means of Discovering the Distance." 48. 57.

'" There was general interest in this use of the principle of
retarded light; e.g., Charles Blagden to Claude Louis Bcrthollet. 24
Oct. 1783. draft, Blagden Letterbook, Yale: Charles Blagden to Sir
Joseph Banks, 25 Oct. 1783, Fitzwilliam Museum Library, Perceval
HI "4.

-''Henry Cavendish to John Michell. 27 May 1783, draft.
Cavendish Mss, New Correspondence. Herschel concluded that the
direction was toward the constellation Hercules; discussed in M. A.
Hoskin, "Herschel. William," DSB 6: 328-36, on 331.

'"Patrick Wilson. "An Experiment Proposed for Determining,
by the Aberration of the Fixed Stars, Whether Rays of Light, in
Pervading Different Media, Change Their Velocity According to the
Law Which Results from Sir Isaac Newton's Ideas Concerning the
Cause of Refraction; and for Ascertaining Their Velocity in Every
Medium W hose Refractive Density is Know n." PT 72 ( 1 782): 58-70.

"Charles Blagden to Sir Joseph Banks, 16 Oct. 1783.
I'itzw illiam Museum Library. Perceval HI 90. This is the second
letter Blagden wrote to Banks that day, a Thursday. In the earlier
letter (Perceval II 184) he said that the night before he had read in J.
J. dc Lalande's latest volume of Astronomy the same idea as Wilson's
for testing the velocity of light. Lalande's work came out in 1781, the
year before Wilson's paper, and moreover. Lalande said that
Boscovich had proposed the method in 1766. Blagden was mortified
that Wilson's paper was allowed to be published in the Philosophical
Transactions. Maskelyne was to blame, he thought, and that evening
he brought it up; Maskelyne became defensive. Blagden described
the testy conversation he had provoked in his second letter to Banks
that night.

"Cavendish to Michell, 27 May 1783.

"Cavendish made a calculation like Michell's on the other
effect of gravity on light, bending it rather than slow ing it. 'There is
no date, but it is vers' late; the watermark on the sheet reads "1802."
It may have been inspired by Michell's paper and perhaps the failed
attempts it led to. It also might have come out of his study of the
orbits of comets, since it is inserted loosely in a packet of papers on
that subject. Henry Cavendish, "'To Find the Bending of a Ray of
Light W hich Passes Near the Surface of Any Body by the Attraction
of 'That Body." Cavendish Mss VIII, 52; in Cavendish. .SVv. Pap. 2:
437. Clifford M. Will, "Henry Cavendish. Johann von Soldner, and
the Deflection of Light," American Journal of Physics 56 (1988):
413-15. J. Fiscnstacdt, "Dc Tinfluence de la gravitation sur la
propagation de la lumiere en thcorie newtonienne. L'archeologie des
troiis noirs." Archive for History of the Exact Sciences 42 (1991 ): 315-86.

i4 Light might be regarded as one of the imponderable fluids.
Bryan Higgins, for example, in his Philosophical Essay Concerning l ight
in 1776, described light as an expansive, atomic fluid that does not
gravitate. His views are discussed in J. R. Partington and D. McKic.
"Historical Studies on the Phlogiston 'Theory. — III. Light and Heat
in Combustion." Annuls of Science 3 (1938): 337-71 . Or light might be
regarded as possessing negative weight; for example. P. D. Leslie, .1
Philosophical Inquiry into the Cause of Animal Heat: With Incidental
Observations on Several Phisiological and C.hymical Questions, Connected
with the Subject (London, 1778), 121.

55 John Michell to Henry Cavendish, 26 May 1783. Cavendish
Mss. New Correspondence.

304

to Cavendish, he did not accept them. Before giving
Cavendish's response, we need to point out that
Michel] believed that a great injustice had been
done to him in the past. His first publication, on
magnetism, is remembered for the first correct and
complete statement of the mathematical properties
of the magnetic force, but for Michel! the importance
of this publication was its practical value for
seamen, w ho were interested not in philosophy but
in compass needles. Michell believed that his
method for making artificial magnets was as good
as that of (Jowin Knight, who made the best
magnets at that time.''' Knight had kept his
method secret, since artificial magnets were a
subject of practical as well as scientific interest,
allied to patents. John Canton also had a secret
method, with which he intended to make money.
W hen Michell published his method in 1750, then
so did Canton the next year." Michell believed
that Canton had taken the method from him.
Michell never forgot or forgave, and Canton was
unhappy about the allegation to his dying day, in
1772; in 1785 the controversy, long pursued
privately, became public. The Biographia Britannica
published a life of Canton in w hich his paper on
magnets was said to have been read in January
1750, one year before it was, the error arising from
the old-style dating. There followed a notice in the
Monthly Review, to which Michell sent a letter
protesting its printing and pressing his claim that
Canton's experiments were "borrowed."* In
response, William Canton, son of John, collected
testimonials for publication. The man in the
middle, Joseph Priestley, friend of both Michell
and Canton, tried w ithout success to get Michell to
retract. Resigned as he was to the imperfections of
the world. Priestley told Canton's son that the
dispute was "one of the inconveniences attending
secrets, of w hich your father sincerely repented." 39

Cavendish thought as Priestley did: the
lesson he drew from the dispute was opposite to
the one Michell did. Whereas Michell wanted
more secrecy. Cavendish wanted none. Cavendish
was happy to receiv e Michell's paper, but he was

sorry however that you wish to hav e the principle
kept secret. The surest w ay of securing the merit to
the author is to let it be know n as soon as possible
and those who act otherwise commonly find
themselves forestalled by others. But in the present
case I can not conceive why you should wish to
have it kept secret for when you was last in town

Cavendish

you made no secret of the principle but mention'd it
openly at our Mondays meeting and if 1 mistake not
at other places and I have frequently heard it talked
of since then. As to the method you propose for
determining whether the \ el. light is diminished
(which seems a vers good one) I do not remember
that you did mention that hut as I do not imagine
that you are likely soon to make any exper. of that
kind yourself 1 see no reason why you should w ish to
keep that secret. On the whole I think that instead of
you desiring me to keep the princ. of the paper secret
you ought rather to wish me to show the paper to as
many of your friends as are desirous of reading it. 4 "

In reply Michell said that the prism was an
afterthought and that it could not, therefore, have
been revealed on his last visit to London. He
remembered having been more discreet and elliptic
than Cavendish gave him credit for. "I thought I
had given some obscure hints," he said, "about the
principle of my paper, to other friends, w hen I was
last in London, yet except what I had said to
yourself, I apprehended they were too obscure to
have the drift of them fully understood." But on the
main point, he yielded: "upon farther consideration,
I believe you are right, and shall therefore have no
objections to your permitting any one, you think
proper to read it; indeed the more people see it the
better, if it is div ulged at all." 41

Cavendish promptly showed Michell's paper
to Maskelyne, Herschel, and others. Cavendish
came to believe that a telescopic lens — Michell's
first thought on the matter — was a better instrument
than a prism for measuring the diminution of light,
and he told Michell that Maskelyne was now of the
same opinion. 4 - Cavendish made a calculation to
show w hat could be expected from a lens: if the

''John Michell, .1 Treatise of Artificial Magnets; in Which Is Shesrn
an Easy and Expeditious Method of Making Them. Superior to die lies/
Natural Ones . . . (Cambridge, 1750), 2. x. 10. 17-20.

"John Canton, "A Method of Making Artificial Magnets
Without the Use of Natural Ones.' - PT 47 (1751): 31-38 .

'"John Michell. letter of 17 May 1785, Monthfy Review 72
(17H5): 47X-HO.

"Michell and Canton's well-known antagonism long antedated
the controversy in 17K5. "| am very sorry lor the difference between
yon and him /Michell/." Priestley wrote to John Canton on 11 Aug.
17oH: in Priestley, .1 Scientific Autobiography, 69—70, on 70. In a letter
to the son William Canton, 20 Aug. 17K.S, Priestley said that he had
tried to get Michell to take hack his accusations. This letter along
with several letters of testimony on Canton's behalf, solicited by his
son, are in the Canton Papers, Royal Society.

-"'Cavendish to Michell. 27 May 17K.V

4l John Michell to Henry Cavendish. 2 July 17H3. Cavendish
Mss. New Correspondence.

'-Henry Cavendish to John Michell. 12 Aug. 1 7K.i, draft.
Cavendish Mss. New Correspondence.

ghied maierial

Sty

velocity of light from a star was decreased by as
small a fraction as 1 in 1000, the focal length of an
achromatic lens would be reduced by 17 parts in
10,000. Maskelyne, he reported, supposed that
even a much smaller reduction in focal length
would be detectable: the alteration of the focus was
5/3rd the alteration of the velocity of light, and
therefore a star with a diameter of only 7 times that
of the sun would, Maskelyne calculated, diminish
the velocity of its light by 1/10,000, which would
be detectable by a good achromatic telescope. 45

These calculations were promising, but
Cavendish had to inform Michell that Maskelyne
had looked at some likely stars with an achromatic-
lens without success, and that Herschel had done the
same on a "great many stars." Herschel was now
grinding a prism to try the experiment Michcll's
way. From these negative findings, Cavendish
concluded that "there is not much likelyhood of
finding any stars whose light is sensibly dimi-
nished." 44 That was in August 1783; two months
later Blagden reported that the astronomers had not
given up but were having instruments made to
continue the search. 45 Three years later he reported
on an instrument "formed like a hook with
achromatic prisms fit all round . . . Blagden added
that no such instrument had actually been built.
Twenty years later, in 1804, Herschel reported on
an experiment on the "velocity of differently
colour'd light" with his forty-foot telescope, on
which subject he had had a conversation with
Cavendish at the Royal Society. 47 The variable
velocity of light was a meaningful concept and a
potentially useful principle in the design of
astronomical instruments until the early twentieth
century, when a nev\ physics was founded on the
absoluteness of the velocity of light.

Michell may have been discouraged by
Cavendish's report. Three months later he still had
not replied to it, and Cavendish sent him a
reminder that he had written a "good while ago." 48
He had forwarded a list of errata compiled by
Maskelyne, and now that the meetings of the
Society were about to begin he wanted to know
what Michell would have him do. Michell sent
instructions concerning the errata, 4 '' but he did not
answer Cavendish's letter for some time. Eight
months passed before he replied to the negative
findings that Cavendish had conveyed. He referred
to his languidness and to other vague reasons for

305

the long delay, and he spoke of his method in a
disheartened vein. Because he had never held
sanguine hopes for the experiment, he would not
be "greatly disappointed in case nothing should
come of it." He went on to acknow ledge Cavendish's
verdict that there might be no stars out there big
enough. 50

It happened that at just this time an astro-
nomical discovery was made that held out hope for
Michcll's method. Regular variations in the bright-
ness of the star Algol were observed by John
Goodricke, a deaf-and-dumb prodigy (who would
die at age twenty-one), whom Michell had never
heard of. In May 1783, the month when Michell
sent his paper to Cavendish, Goodricke submitted
his paper on Algol, for which he was awarded the
Copley Medal of the Royal Society. 51 Goodricke
guessed (correctly) that the reason for the variation
of Algol was that it was a double star; a second
body revolved around the bright star, periodically
cutting off its light. Michell contrived a theory of
its variations, confessing that it required the
"concurrence of so many circumstances" that it was
improbable. 5 - By assuming that Algol was a double-
star and that the central star was both larger and
duller than the other, and by inventing hypotheses
about the eccentricity and orientation of the orbit,
Michell accounted for the regularities that
Goodrickc had observed in the variation of the
light from Algol. He thought that if his explanation
was correct, his prism test would "almost with

4 'Maskclync's calculations, in his hand, arc on a sheet enclosed
in Cavendish's draft of his letter to Michell. 27 May 1785.
•"Cavendish to Michell. 12 Aug. 1785.

«Charles Blagden to Claude Louis Bcrthollet, 24 Oct. 1785,
draft, Blagden Letter/book, Vale.

4l, Charlcs Blagden to Pierre Simon Laplace. 51 May 1 7K6. draft,
Blagden Letterbook, Royal Society. 7:1.

47 William Herschel to Patrick W ilson. 26 Dec. 1804. copy. Royal
Astronomical Society, Herschel Mss, Wl/1, pp. 255-56. Cavendish
asked I Icrschcl if he had seen a recent article on the velocity of heat
rays in the Philosophical Magazine. This new journal Cavendish
subscribed to and read.

4 "Ilcnry Cavendish to John Michell. 4 Nov 1 7HA. draft.
Cav endish Mss. New Correspondence.

4,, John Michell to Henry Cavendish. 10 Nov. 1785. Cavendish
Mss, New ( lorrespondence.

"•John Michell to Ilenrv Cavendish. 20 Apr. 1784, Cavendish
Mss. New Correspondence.

5, John Goodricke, "On the Periods of the Changes of Light in
the Star Algol," and "A Series of Observations on, and a Discovers
of, the Period of the Variation of the Light of the Bright Star in the
Head of Medusa, Called Algol," PT 75 ( 1 783): 474-S2. and 74 ( I 784):
287-92.

"Michell to Cavendish. 2 July 1785.

306

certainty" confirm it. Cavendish was again deflating:
"I imagine you rather wish than think it to be likely." 5 -^

Algol held an interest for Cavendish apart
from Michell's method, though this too was
connected with Michell. In their correspondence
about his method, Michell told Cavendish of an
instrument he had invented for measuring the
comparative brightness of stars. Michell proposed
calling his instrument an "astrophotometer," since
a "hard name adds much to the dignity of a
thing." S4 "I like your Astrophotomer very well,"
Cavendish replied. He too wished that observations
of that kind were made, and he went on to describe
a contrivance for the same purpose he had earlier
designed. His photometer employed the reflection
from a speculum to bring the brightness of one star
into equality with that of another. 55 Cavendish and
Aubert both measured the light from Algol, 5 '' and
with a photometer made to his design, Cavendish
and Blagden observed Algol together. Cavendish's
photometer did not work very well. 57

Cavendish's involvement in Michell's work
was immediate. The subject belonged to the far-
reaching implications of the unity of the
Newtonian world, and Michell developed a
dynamics of stars based upon the pervasive action
of forces. The members of multiple systems of
stars orbit about each other by reason of their
mutual grav itation. They expel and accelerate light
by enormous forces, as Michell had calculated for
Priestley's History of Optics, and they attract it back
by the almost infinitely weaker but infinitely
extended force of grav ity. The particles of starlight
are once again accelerated by strong forces in glass
prisms when they are received on earth. The forces
of the light, the glass, and the stars determine a
unique, calculable path of light in the prism. It
together with the motions and apparent
dimensions (if observable) of the multiple stars
determine the crucial magnitudes of sidereal
astronomy: the distances, sizes, and masses of the
stars. Michell's method brought together the two
exact sciences of planetary theory and optics, one
the science of the greatest bodies of the universe
and the other the science of the minutest bodies.
Just as Newton had used his grav itational mechan-
ics to determine the local motions of the solar
system, Michell sought the motions and measures
of the universe beyond the solar system by the
same methods. Michell and Cavendish's collabora-

Cavendish

tion was an affirmation of the tradition of the
mathematical physics of forces.

Aerial Telescope

No sooner had Cavendish setrled into his
new house at Clapham Common than he took the
first step toward erecting a large telescope on the
premises. Given the timing, the suggestion is that
Cavendish had wanted to try this telescope and
was only waiting until he had a place for it.
Christiaan Huygens, the builder of the telescope,
had described its needs: "In a large area every way
open to the view of the heavens, let a long pole or
mast be fixt upright in the earth." 58 Cavendish
followed directions.

The telescope had been given to the Royal
Society in 1691 by Constantine Huygens, then
secretary to King William III. Constantine was a
telescope-builder like his brother Christiaan,
though it is Christiaan who is generally credited
with introducing telescopes of this sort, the so-
called "aerial." The telescope in question is usually
(and slightly inaccurately) referred to as Huygens'
123-foot telescope. 5 '' The incentive to develop
telescopes of such extraordinarily long focal lengths
in the first place was to reduce aberrations and also
to achieve high magnifications. 60 Not until John

"Cavendish to Michell, 12 Aug. 1783.

'Michell to Cavendish. 2 July 1785. Michell's instrument was a
variant of one proposed in 17(10 by R. I'. Francois-Marie, as reported
in Pierre Bouguer, Optica/ Treatise on the Gradation of Light, 1700.
trans, with notes by W. Knowlcs Middleton ( Toronto: I Diversity
of Toronto I'ress, 1%I ). Bouguer's principles appear throughout
Michell's astronomical writings.

"Cavendish to Michell, 12 Aug. 1783.

"Charles Blagden to Charles l.e Roy. 15 Sep. 1785. draft,
Blagden Letterbook, Vale.

"Charles Blagden to Sir Joseph Banks. 16, 23. and 30 Oct. 1783,
Tit/.william Museum Library, Pcrcival H190, 11193, and H195.

"■"Robert Smith, .1 Compieal System of Opticks in Four Hooks, viz a
Popular, a Mathematical, n Mechanical, and a Philosophical treatise. To
Which Are Added Remarks upon die Whole, 2 vols. (Cambridge, 1738)
2:353.

5 The accurate dimensions of this telescope are: focal length 122
feet and aperture 7 7/8 inches. Constantine Huygens also gave the
Royal Society two other object-glasses of even greater focal length.
170 feet and 210 feet, and Cavendish evidently borrowed them too.
R. A. Sampson and A. E. Conrady, "On Three Huygens Lenses in
the Possession of the Royal Society of London," Proceedings of the
Royal Society of Edinburgh 49 (1929): 289-99, on 289-92.

w 'Thc 123-foot Huygens telescope has a magnification of 218.
William Kitchener. The Economy of the Eyes. Part 2: Of Telescopes : Being
the Result of Thirty Years' Experiments a-i/h Fifty-One 'Telescopes, of from
One lo Sine Inches in Diameter (London. 1825). 22. The very slight
curvature of the long focal-length lens greatly reduces spherical
aberration. Chromatic aberration is also practically eliminated for the
following reason. 'The telescope consists of two lenses, neither of

CopynghtM ma

A7t

307

Hadley developed the Newtonian reflecting
telescope did astronomers know of any way to
improve their telescopes other than by lengthening
the tubes, which was a deadend, for the length
increased faster than the magnification: to double
the magnification, the length had to be quadrupled,
to triple it, the length had to be increased ninefold,
etc. Huygens showed astronomers that they could
dispense with the unwieldly rigid tubes for mount-
ing the object-glass and eye-glass; this in turn
made possible much longer telescopes.

With Huygens' aerial telescope, the object-
glass was fixed to the top of a tall pole, and the
observer aligned the eye-glass with the help of a
taut thread/' 1 This telescope was as hard to use as it
sounds. The Royal Society considered fixing the
telescope to a tall, solid building, but they could
not settle on any tall enough or solid enough.
Halley was ordered to consider the scaffolding of
St. Paul's Church. James Pound mounted the
telescope on a maypole, removed from the Strand
and relocated in Wanstead Park. Pound made
improvements on the "furniture and Apparatus,"
but the pole broke, as his collaborator Bradley
explained when he returned the telescope to the
Society in 1728. The main improvement was a
micrometer, which gave Huygens' telescope its
one advantage over the Newtonian; the longer the
telescope, the larger the image, and the micrometer
measures a large image more accurately than a
small image. The telescope was borrowed again by
William Derham, who explained why he was
returning it in 1741: "The chief inconvenience is
the want of a long pole of 100 or more feet, to raise
my long glass to such a height as to see the
heavenly bodies above the thick vapours," and he-
was told that this would cost him eighty or ninety
pounds, which was beyond his means. Next, in
1748, Lord Macclesfield borrowed the telescope
for mounting at Shirburn Castle, 6 - and Lord
Charles Cavendish was one of the Fellows who
conveyed it from the Royal Society to Shirburn
Castle. 63 A visitor wrote of going to Shirburn to
"look at Jupiter through one of Mr. Huygens' long
telescopes," which revealed "that bright planet in
perfection. " w In 1778 Nevil Maskelyne borrowed
the long, 210- foot Huygens telescope. 65

At this juncture, Henry Cavendish enters
the history of Huygens' telescopes. In November
1785 the council of the Royal Society gave

Cavendish permission to borrow the 123-foot
telescope and other object-glasses. He brought the
telescopes to Clapham Common, where he kept
them for three years, 66 and where he built a proper
mount. Huygens had told how to prepare the mast,
secure it in the ground, and make it climbable, and
how to lengthen or shorten the thread by a peg that
turned, as on a musical stringed instrument.
Among Cavendish's manuscripts is a study of a
ship's mast, which we take to be the mount for the
Huygens telescope. It begins with fundamentals:
"According to Newton the resistance of wind to a
globe is equal to . . . and therefore if wind is 60
miles per hour . . . ." In this vein Cavendish
determined the pressure of wind on two cylinders
of unequal diameters each forty feet in length. To
judge from his calculations, the Huygens telescope
was erected on a wooden mast 80 feet high and
tapered from 23 inches in diameter at the bottom
to 13^ inches at the top. It was supported by 20-
foot strutts planted 11 feet from the base. A
horizontal piece was fixed to the mast. 67 The mast
towered above Cavendish's house as if it were the
home of a nostalgic man of the sea. To the

which is achromatic, but if the two lenses arc made of glass of the
same dispersion and the telescope is focused at infinitely distant
objects, such as stars, the angular magnification for any given color
depends only on the curvature of the lenses and not on the refractive
index. The workmanship on the Huygens lenses was of high quality
but not the glass, which compares poorly with today's cheapest bottle
or window glass. The tangle of fine veins in the glass made the
refraction irregular. The glass available to Huygens resulted in poor
definition of images, as Cavendish no doubt determined: this bore-
on his and Herschel's interest in indistinct images. Sampson and
Conrady, "On Three Huygens Lenses." 298-99.

'■'Smith. A System of Opticis, 354. Christiaan Huygens'
explanation of the working of the aerial telescope is quoted in
Sampson and Conrady, "On Three Huygens Lenses." 298. The
observer stood, resting his arms on a light frame or hurdle, and
holding the eyepiece (concentric, adjustable metal tubes containing
the eye-glass) by the handle. A cord connected it with a short board,
upon which the objective was mounted at one end and a counterpoise at
the other. By tension on the cord the observer could bring the two
lenses into parallel.

"Smith, Op/iris, ,554, 440. R, S. Rigaud, "Memoirs of Or. James
Bradley," James Bradley, Miscellaneous Works and Correspondence of the
Rev. James Bradley, D.D., F.R.S., ed. S. P. Rigaud (Oxford, 1832). ix,
Ix. Ixxxiv. Royal Society, JB 13:237 (20 June 1728). Royal Society,
Minutes of Council 4:5^8 (10 and 29 Aug. 1748). King, History of the
Telescope, 63.

'•'Charles Vorke to Philip Vorke, 23 Aug. 1748, BL Add Mss
35360, f. 185.

'''Catherine Talbot to Elizabeth Carter, 10 Oct. 1748, in A Series
of Letters lletaeen Mrs. Elizabeth Carter and Miss Catherine Talbot from
the Year 1741 to 1770 etc., vol. 1 (London, 1809). 293-94.

"Royal Society, Minutes of Council 5:369 (10 Dec. 1778).

"■Royal Society. Minutes of Council 7:134 (17 Nov. 1785).
Cavendish returned the telescope on 13 Nov 1788.

,,7 The computations for the mast are in Cavendish Mss, Misc.

308

neighborhood it was the most conspicuous sign of
Cavendish's scientific vocation. Well built, the mast
remained in place after Cavendish had returned
the I luygens telescopes and long after his death. A
much later description of Cavendish's property
reads: "In a paddock at the back of the house is a
mast of a ship, erected for the purpose of making
philosophical experiments."' 1 *

A half year after borrowing the I luygens
lenses. Cavendish still had not tried them on
objects on the land, Aubert told Herschel, but he-
was busy on an apparatus (the mast) for trying
them on celestial objects.'''' Then, in June 1786,
Blagden told Berthollet that ( lavendish was ready
to "make a trial of the old aerial telescopes."
I lerschel looked forward to the trial for "comparing
the effect with that of his large reflectors." 7 "
Blagden told Benjamin Thompson that 200-plus-
foot telescopes would probably be found inferior to
Herschel's big reflectors, but still it was "desirable
to form a just estimate of the tools with which our
ancestors worked." 71 That does not mean that
Cav endish acted out of historical curiosity or out of
a desire to resurrect the aerial telescope in practice,
since it was unvv ieldly and the art of telescopes had
advanced. Cavendish went to trouble and expense
because of fundamental (juestions about optics and
telescopes. Herschel came to Clapham Common to
participate in the trials, as did the instrument-
maker Peter Holland, whose father, John, had
shown how to eliminate one of the major aberrations
(chromatic) of telescopes. 'There was a party of
scientific witnesses. Holland found that his forty-six-
inch triple-lens, achromatic refractor, his "Dwarf,"
was "fairly a match for the [123-foot] Giant." 72
Cavendish ev idently was the last person to mount
I luygens' telescopes for celestial observations,
though the "Giant" continued to draw interest. 75 Cav-
endish's experiments w ith I luygens' object-glasses
of the Royal Society undoubtedly were connected
with, and help date, a large body of mathematical
studies of his on the aberration of lenses.

Indistinct Vision

John I lerschel told an anecdote about his
father, William, and Henry (lavendish. The year
was 17K6, and the setting was a dinner given by
Aubert at w hich I lerschel and Cav endish sat
together. Cavendish was his usual silent self until
suddenly he said to his table companion, "I am

Cavendish

told that you see the stars round. Dr. Herschel."
"Round as a button," Herschel replied. Cavendish
relapsed into silence until tow ard the end of dinner
he asked in a doubtful voice, "Round as a button?"
"Exactly, round as a button," and with that
Herschel brought the conversation to an end. 74 It
was a stor\ about Cav endish's legendary taciturnity,
told at his expense, but the year and the subject
can be given an historical reference: in 17<S6, in the
year of the dinner at Aubert 's and likely as a result
of that dinner, Cav endish entered into Herschel's
scientific work on optical images.

When Herschel took up astronomy, it was
almost unthinkable that stars seen in telescopes
would not show tails and rays. Herschel's claim that
with his high-power telescopes stars appeared
round and well defined, like buttons, was met with
raised eyebrows, and not just Cavendish's. Four
years before the dinner at Aubert 's, in 1782, Dr.
William Watson w rote to Herschel that Aubert and
Maskelyne had never seen stars without aberration
and that they doubted that Herschel saw them
"round and well defined." Herschel wrote back
that he was "surprized" that Aubert and Maskelyne
had not seen stars as he did, which was not without
aberration but " round and well-defined" nonetheless.

W J. II. Michael Burgess, The Chronicles of Clapham /Clapham
Common/. Being a Selection from tin Reminiscences of Thomas Parsons,
Sometime Member of the Clapham .\>it'n/iuiri/iii Society ( London:
Ramsdcn, \<>2<». 57.

'•''Alexander Aubert to William Herschel. 23 Mar. 1786. Royal
Astronomical Society Mss. Herschel W.I/13. A23.

"'Charles Warden to C. I.. Berthollet. draft, S June 1786.
Blagden Lcttcrbook, Royal Society. 7:'.

"'Charles Blagden to Benjamin Thompson, draft, 7 July 1786.
Blagden Lectcrbook, Royal Society. 7.

' 2 This is what Holland told William Kitchner, The Economy of the
Eyes, 22.

"Out of historical curiosity, the astronomer W. H. Smyth
considered setting up the telescope again, around 183.S: "I was so
puzzled to know how they contrived to get the eye and object-
glasses of these unwieldly machines manic/I. or brought parallel to
each other lor perfect vision, and so desirous of comparing the
performance of one of them, that I was about to ask the Roval
Society's permission to erect the aerial 123-foot telescope in their
possession. The trouble, however, promised to be so much greater
than the object appeared to justify, that I laid the project aside."
Ouoted in Charles Richard Weld. .1 History of the Royal Society. 1 vols,
in 1. 1848 (New York: Arno Press. 1975), 331. In 192" Sampson and
Conrady examined the two I luygens lenses of longer focal lengths
but not the 123-foot lens. To determine the focal lengths, they used
an interferometer. To determine the radii of curvature, they also
relied on interference phenomena, since the extreme shallowness of
the curvature of the long focal-length lenses precluded the use of a
spherometer. Sampson and Conrady. "On Three Huygens Lenses."
pp. 294-97.

74 John Herschel's recollection in Lubboc k. The Herschel Chronicle,

l(l_'.

Copy rig hied material

Sly

Herschel's mirrors were polished so accurately that
the aberration was symmetrical, the images round. 75
The question of the indistinctness of vision
prompted a kind of collaboration between
Herschel and Cavendish in 1786. When Herschel
had begun observing the heavens with his
Newtonian telescope using high powers of
magnification, he had come across statements by
authorities that would discourage this practice.
There was one by Huygens, for example, quoted
in Smith's System of Opticks, and there was another
closer to home by Michell, reported in Priestley's
History of Optics. Priestley wrote of the "remarkable
indistinctness of vision" that occurs when the
pencils of light that form the image of an object are
very small, contrary to expectation. Unable to find
an account of this fact in his sources, Priestley
turned to Michell, who told him that the best way
to observe the indistinctness was by narrowing the
aperture of a telescope. Michell carried out some
experiments along that line: by viewing a flame
and the sun through tiny but measurable
perforations in a card, Michell calculated that the
indistinctness was present with pencils less than
l/30th of an inch across. There was "very little, if
anything, gained by increasing the magnifying
power of telescopes" if it meant reducing the
pencil below this limit, even if there was sufficient
light to see by; to Michell the explanation of
indistinctness lay not in the telescope but in "some
unknown peculiarity in the structure of the eye." 7 ' 1

If Michell was right, Herschel was wasting his time
observing with high magnifying powers. But both
parts of Michell's conclusion, the anatomical cause
of indistinct vision and the consequent absolute
limitation on the perfectibility of telescopes,
conflicted with Herschel's experience with his
telescopes. In 1778 he had done experiments to
confirm his doubts about the alleged limitation of
telescopes, and in a paper in 1781 on the parallax of
the fixed stars, he brought forward his doubts.
Theories about telescopes take too much "for
granted": they tell us that "we gain nothing by
magnifying too much," but until we can see better
with lower magnifications, we should not condemn
"too much" magnification. "I see no reason,"
Herschel concluded, "why we should limit the
powers of our instruments by any theory." 77
Herschel urged other astronomers not to be

309

deterred from joining him in his laborious but
promising study of double stars, for their telescopes
should give, as his did, images of stars "perfectly
round and well-defined." With regard to indistinct
vision, theories conflicted not only with Herschel's
experience with telescopes but also with experi-
ments done with microscopes made of single-lens
globules. These microscopes were notable both for
their distinctness of image and for their high
powers of magnification, of the order of 10,000,
from which it followed that their the optic pencils
at the eye were not greater than 1 /2,500th of an
inch in diameter. Distinctness, for I lerschel, was
determined by the perfection of the lens or
speculum and not by the eye.

"Late conversation with some of my highly
esteemed and learned friends," who certainly
included Cavendish, in 1786 prompted Herschel to
write up his old experiments in the form of a paper
for the Philosophical Transactions. 1 * For this paper
Herschel wanted to know exactly what the
authorities had said about indistinct vision, and
through Blagden he borrowed books from Cavendish
to look it up. 7 '' Blagden spread word of Herschel's
new work weeks before his paper was read to the
Royal Society. 8 "

Herschel looked with the naked eye
through minute holes in a brass plate at printed
letters, which he could read even though the
pencils were much less than l/4()th or l/50th part
of an inch, only l/244th part. Then with a two-lens
microscope, he produced pencils no greater than
1/2,1 73rd part of an inch, with which he could see-
the bristles on the edge of the wing of a fly. Finally,
he varied the aperture of the object lens of the

"Herschel's correspondent was the son of William Watson, the
electrician who was awarded the Copley Medal. Dr. William Watson
to William Herschel. 4 Jan. /1782/. quoted in J. B. Sidgwick, William
Herschel. Explorer of the Heavens (London: Faberand Faber, 1955). 80.
William Herschel to Dr. William Watson, 7 Jan. 1782, quoted in
Lubbock. The Hershel Chronicle, 101. "Herschel. Sir William." DNB
9:719-25, on 724.

"Priestley, The History and /'mm/ State of Discoveries Relating in
Vision 2:7X4-8.5.

"William Herschel. "Investigation of the Cause of that
Indistinctness of Vision Which Mas Been Ascribed to the Smallness
of the Optic Pencil," PT 76 (1786): 500-507, on 500-501: "On the
Parallax of the fixed Stars." /7'72 (1782): 82-1 1 1. on 92. 96.

'"Herschel. "Investigation of the Cause," 501.

"Herschel, "Investigation of the Cause." 501. Blagden to
Herschel. draft, 19 May 1786. Blagden Letterbook, Royal Society,
7:762.

""Blagden to Berthollet. draft, 5 June 1786, Blagden Letterbook.
Royal Society. 7:2.

310

microscope until it was very small in proportion to
the focal length. Indistinctness resulted from the
smallness of that proportion, not from the smallness
of pencils, Herschel concluded. Hcrsehel wrote up
this conclusion, but before his paper was read to the
Royal Society, he wanted Cavendish to read it.

Although Cavendish found that HerschcTs
experiments with the microscope were "curious c\
very well deserve attending," he found in them an
indistinctness of a kind unacceptable to him;
namely, an unthorough investigation and an
incomplete description of what was done.
Cavendish's optical manuscripts contain calcula-
tions testifying to his efforts to make intelligible
Herschel's paper. He found an error in the
diameter of the optic pencil in the eighth
experiment but that was incidental. He had two
major criticisms. First, he could not judge the
"degree of force" of the experiments because
I lerschel had not given the proportion of aperture
to focal length in experiments with distinct vision as
well as those with indistinct. Herschel accepted
this criticism and asked William Watson, jun., to
give back the microscope with which he had made
his original experiments so that he could determine
this proportion exactly. The measures appeared in
the published version of the paper. Second,
I lerschel had done no more than to describe his
experiments; there were, after all, well-known
causes of indistinctness of optical images. (In the
case of refracting telescopes, they were discussed,
for example, by John Holland, w ho showed how to
eliminate one of the causes, chromatic aberration,
and how to reduce the other, spherical aberration,
in eye glasses. 81 ) Cavendish wrote to Herschel:

It deserves to he considered that though what
Huygens supposed about the smallness of the
pencils is difficult to account for yet yours is much
more so as his may depend on the manner in
which the sensation of the retina is affected by-
light which is a subject we know very little of
whereas in your supposition I think only the
refraction of light through glass can be concerned
which is a subject we know much more of. For
this reason it can not he expected that anyone
should assent to your hypothesis without good
proof & accordingly we will wish to examine
whether the appearances you observed may not
depend on some other cause, for this reason I
think it would be much more satisfactory if you
would set down in all the experiments not only
the diameter of the pencil & proportion of the
aperture to the focal length but also the

Cavendish

magnifying power & the degree of indistinctness
which ought to arise from the aberration is:
difference of refrangibility in the object glass &
any other circumstances which may he supposed
to influence the exper.

Herschel acknowledged that he did not assign a
"Physical cause" to indistinctness but only gave a
hint as to the existence of one, but even if "we
should never know the physical cause," the
experimental connection between indistinctness
and lens proportions had a practical value. He told
Cavendish that he would conclude bis paper with
his "wish that what I had said might be looked
upon etc," as he did.* 2 He was kept from doing
more experiments with a view to "submitting this
cause of optical imperfection to theory" because of
his work on his forty-foot reflecting telescope. In
any case, his intention was only to give the
experiments and leave the rest to the "theoretical
optician."*" Herschel's interest was, after all,
primarily in telescopes and in his work with them,
the determination of the contents, size, and
structure of the universe. Herschel was finished
w ith this side inv estigation for now, but Cav endish
was not, it would seem. Cavendish left a number of
undated, theoretical papers in manuscript on the
aberration in reflecting and refracting telescopes.
Several of them are carefully drafted, with
corrections, evidently written to be shown to
someone. One of them is titled "On the Aberration
in Reflecting Telescope Used in Herschels Man-
ner."* 4 Cavendish rarely spoke in company but
w hen he did, it was precisely to the point. "Round
as a button?" stuck w ith I lerschel.

We leave the subject of indistinct vision
where it began for Herschel, with John Michell.
Blagden sent Herschel's paper to Michell, who
then wrote to Cavendish about it. Herschel was
wrong, he said, to think that his distinct images

"'John Dolland, "A Letter . . . Concerning an Improvement of
Refracting Telescopes," FT 48 (1753): 103.

"Cavendish to Herschel. draft, n.d. /after \1 June 17W>/;
Herschel to Cavendish, M June 17Wi. Cavendish Mss, New
( lorrcspondence. I lenry Cavendish, "Relating to 1 Icrschcls Kxper on
Indistinct Vision in Telescopes." Cavendish Mss V. 13.

" Herschel. "Investigation of the Cause." 507.

""Henry Cavendish. "Of the Figure of Classes Necessary to Bring
Rays to a Focus & of the Aberration of Rays"; "Aberration in Reflecting
Telescope Pointed to Near Object When the Figure of the Specula Arc-
Adapted to Distant Ones"; "On the Aberration in Reflecting 'Telescope
I'sed in Herschels Manner"; "On the Aberration of Rays Passing
Through Spherical I. ens." Cavendish Mss V, 7. 8, 10, 11.

Copy rig hi M

contradicted Huygens, and he reminded Cavendish
of the explanation he gave him at the Royal
Society for the images. Herschel's findings were of
great value to the "optical world" but not because
of what they taught about telescopes but for what
they implied for the "natural history of the eye." 85

Comets

From the 1780s Cavendish devoted a large
body of work to the orbits of comets, beginning, it
seems, with the "comet" discovered by Herschel
in 1781; Cavendish made computations from
observations made of it by Maskelyne and Thomas
Hornsby, who rejected the fashion of calling it a
"planet" since it was a comet (it was, in fact,
Uranus).* 6 The next dated work we come upon in
Cavendish's papers is his own method for com-
puting the orbits of comets. Herschel was again the
instigator, only this time it was Herschel brother
and sister. Caroline Herschel worked with her
brother at the observatory, and when he was away
she made sweeps of the sky herself, in the course
of which she became renowned as a discoverer of
comets, eight in all. Blagden at the Royal Society
was informed directly by her of her first comet, in
1 786, and also by Aubert. 87 When she discovered an-
other comet in 1788, Cavendish observed it himself. 8 *

Newton had laid down that comets moved
on a parabolic path, which in the case of a returning
comet coincided with a highly eccentric ellipse. In
principle, three observations would determine the
elements of the path; in practice it was a difficult
problem, a challenge to mathematical astronomers.
A forty-year-old method by Boscovich had recently
been rejected by Laplace, leading to an
acrimonious dispute, and capturing the attention of
calculators. As a test of their methods and their
skill, astronomers eagerly looked forward to the
return of a comet in late 1788. 8 '' The mathematical
problem was to find the distortion of the path of
the comet by the great planets Jupiter and Saturn
as the comet left the solar system, since this would
affect the exact timing of its return. The French
Academy announced a prize for the best solution.
Maskelyne published a paper "in order to assist
astronomers in looking out for this comet," and
Cavendish corresponded with Maskelyne about
the method of it. 90

Cavendish now immersed himself in the
general problem of determining the paths of

comets.'" Finding Laplace's method wanting, 1 ' 2 he
devised one of his own, with which he planned to
determine the orbit of Caroline Herschel's comer.
Cavendish's method, which entailed covering a
globe with white paper, proved tedious in practice,
and he told Maskelyne that he planned to hire
someone to draw up the tables for it. 4 -' Ten years
later Cavendish and Maskelyne collaborated on
computing the path of another comet; by this time
Cavendish was using Boscovieh's method, which
he thought was very accurate/' 4 The immense
labor Cavendish devoted to the paths of comets is
to be understood only partly in terms of the
technical challenge of the problems astronomers
were grappling with at the time. Once regarded as
transient phenomena of the atmosphere, comets
were one of the triumphs of the Newtonian world

" s John Michcll to Henry Cavendish, 8 Nov. 1786, Cavendish
Mss. New Correspondence.

■"Hornsby, too. supported by Cavendish's computations,
thought that Herschel's observations were off. Herschel thought
otherwise. Thomas Hornsby to William Herschel. 26 Feb. 1782;
William Herschel, "Memorandum for Mr Cavendish," in Lubbock.
Herschel Chronicle, 1 06-7.

"'Blagden announced the discovery to the astronomers at
Greenwich on the recent visitation. On the coming Sunday, he said,
if the weather was clear, he. Banks, and others were going to
Caroline Herschel's to look at the comet themselves. Charles
Blagden ro Claude Louis Berthollet and Benjamin Thompson. 4
Aug. 1786, drafts, and to Caroline Herschel, 5 Aug. 1786. draft,
Blagden Lettcrbook. Royal Society, 7:18-20. "In consequence of the
friendship which I know to exist between you and my brother," she
wrote to Blagden. in the introduction to her paper she sent him:
Caroline Herschel, "An Account of a New Comet," PT 11 (1786):
1-3. She asked Blagden to communicate her discovery to her
brother's other friends, and he did.

"""Miss Herschels Comet," Cavendish Mss Mil. .V7.

"'Charles Coulston Ciillispie, "Laplace, Pierre- Simon, Marquis
de," DSB 15:273-356, on 309-10.

'"'We assume that Maskelyne was the "you" referred to in
Henry Cavendish, "In Order to Compute the Return of a Comet."
Cavendish Mss. \ III, 39. Nevil Maskelyne, "Advertisement of the
Expected Return of the Comet of 1532 and 1661 in the Year 1788."
PT 76 ( 1 786): 426-31, on 429.

'"Charles Blagden to Mrs. Grey. 5 Oct. 1786. draft, Blagden
Lettcrbook, Roval Society, 7:39.

''-"La Places Method," Cavendish Mss VIII, 41 .

''''Henry Cavendish. "Method of Finding Comets Orbits Fair."
Cavendish Mss, III, 43. This paper of 37 pages, written in fair copy,
was given to Maskelyne and returned. In another bundle of comet
calculations is the draft of Cavendish's reply to Maskelyne.
unaddressed and undated: Cavendish Mss VIII, 54.

" This exchange begins w ith observations of a comet sent by
Maskelyne to Cavendish together with a request for Cavendish to
compute its elements. Nevil Maskelyne to Henry Cavendish. 4. 8,
and 9 Oct. 1799: there is an undated draft of a reply from Cavendish
that begins, "Since my letter of last 'Thursday . . ." Cavendish Mss
VIII, 46. Henry Cavendish. "Kxample of Computing Orbit on Bosc.
Principle W ithout Graphical Opcrat."; "Comet of 1799 Computed by
the 'Table for Boscovic's Sagitta": "Comet of 1799"; "Computation of
Comet of 1799 bv Fluxional Process"; "Boscovic's Method of F inding
the Orbit of a Comet," Cavendish Mss VIII, 42, 44, 46. 47. 50.

312

Cavendish

system; these seemingly capricious objects were
found to be subject to the force of gravitation and
so to theoretical calculation. 95 We recall the earliest
record we have of Cavendish's thoughts, the poem
from his Cambridge years: nature mocks, but "She
does lay bare hidden causes/ And the wandering
paths of the stars." Cavendish's study of comets in
his later years can be seen as a v indication of that
thought (and, perhaps, of his calling).

Published Work

None of the examples we have given so far
of Cavendish's work in astronomy was published.
We now turn to what he did publish; his last five
papers in the Philosophical Transactions. They all had
to do directly or indirectly with astronomy, though
only one of them was a major work, his continuation
of Michell's experiment of weighing the world,
which we discuss separately. Another of these
papers was a note on the aurora borealis, a subject
which by method and practitioner belonged equally
to astronomy and to meteorology. Still another was
a note about a method in nautical astronomy, a
comment on a recent paper by Mendez y Rios (a
highly technical point, which led nowhere and
which we will pass by). 1 "' Two others are more
substantial, a study of the Hindoo civil year and a
method of dividing astronomical instruments.

Although meteors were regarded by some
as terrestrial comets, 1 ' 7 they had not been subjected
to calculation in the way comets in the sky had.
One of Aubert's very few publications was on two
meteors he saw in 17H.V So little was known about
them, Aubert said, that as many accounts as
possible of them should be collected "to enable us
to form some idea of their nature, path, magnitude,
and distance from the earth." 98 In that same year,
1783, Blagden and Maskelyne, independently, sent
out queries about meteors. 99 In his query, Blagden
recommended a standard practice for observers of
meteors, much as Jurin had early in the century for
observers of the weather. An obvious problem for
observers was the speed with which meteors
moved; Blagden gave calculations by Herschel,
Aubert, and Watson that suggested twenty miles
per second, or ninety times the speed of sound. In
principle, the pocket watch was an all-important
instrument for observers of meteors, but the
"emotion felt by the spectator" usually rendered
the watch useless, and other points of reference

were needed. To know their height and velocity,
observations needed to be made by "different
persons in concert at distant stations." 100 Blagden
thought that meteors were masses of electric fluids
attracted to or repelled from the earth's poles, and
he anticipated that observations of them would
lead to the law s of motion of the electric fluid in
empty spaces, laws which could not be learned
from "our small experiments" in the laboratory.
The aurora borealis, Blagden believed, was 'an
electrical phenomenon of the same nature only
higher in the sky. 101

In the eighteenth century, "meteors"
included the aurora borealis; "meteors of the aurora
kind," as Cavendish called them. 10 - Auroras
borealis were observed by Cavendish with "much
attention," his brother, Frederick, noted in 1 780. "'^
By then Cavendish was already computing their
coronas. 104 In 1790 Cavendish published an
account of an aurora that had been observed six
years earlier by three persons, one of whom was
the Cambridge scientist Francis John Hyde
Wollaston (whom we will meet in our discussion of
the experiment of weighing the world). Their
accounts were communicated to the Royal Society

95 A. Wolf, .1 History of Science, Technology c? Philosophy in tin- 16th
& Hth Centuries, vol. I (New York: I larpcr & Brothers. 1959), 159-60.

% Mendoza y Rios's object was to give general formulas from
which the different methods of nautical astronomy can he deduced
and compared. He said that Cavendish gave him this method and
permission to publish an extract from his letter (probably arising
from the committee of papers). It is printed at the end of Josef de
Mcndoza s Rios. "Recherchcs stir les principaux problems de
I'astronomie nautiquc." I'/'Hl (1747): 43-122: "Addition. Nontenant
tine methode pour rcduirc les distances lunaires," 114-22: "Extract
of a Letter ... to Mr. Mendoza y Rios. January, 1745," in Cav endish.
Set. I'rtp. 2:246-4K.

'"That was John Pringlc's theory, for example .

''"Alexander Aubert. "An Account of the Meteors of the 1 Hth of
August and 4th of October. 17K3," / J 7'74(1784): 112-15, on 112.

'"Charles Blagden to Joseph Banks. 16 Oct. 17X3. Fitzwilliam
Museum Library, I'crcival 11190.

""Charles Blagden. "An Account of Some Late Fiery Meteors;
with Observations." FT 74 ( 1 784): 201-32. on 217-1X. 224.

1,11 Ibid.. 224. 231.

"'-'Henry Cavendish. "On the Height of the Luminous Arch
Which Was Seen on Feb. 25. 17X4." IT HO ( 1 790): 101-5; Set. Pap. 2:
253-55, on 233.

""From Market Street, north of London, where he lived.
Frederick Cavendish wrote to his brother, Henry, at their father's
house in Orcat Marlborough Street. The night before. Frederick had
seen an aurora borealis, the most remarkable he had ever seen. "It
had the most perfect Corona 1 ever beheld, with Radii streaming
down on all sides, and over-spreading the whole Hemisphere."
Frederick gave a clear and precise description of it. consulting his
atlas of the stars to locate it. Letter of I Mar. 17X0. Cavendish Mss
X(b), 9; Set. Pap. 2:69.

'"Mlcnry Cavendish, "Computation of Corona of Aurora
Borealis on Feb. 26. 177X," Cavendish Mss. Misc.

Sty

in 1786 and published in the Philosophical
Transactions in 1790. Cavendish's purpose in drawing
attention to them was to encourage "people to
attend to these arches" in order to test his
"hypothesis," which was that the aurora consisted
of parallel rays of light shooting skyward. Should
this hypothesis be confirmed, it would then lie a
proper "theory." 105 At the same time that he was
studying the aurora borealis, Cavendish was
requesting information about the other sort of
meteor, the terrestrial comet or whatever it was. 106

At the time of his paper in 1 792 on the civil year of
the Hindoos, Cavendish was a subscriber to the
Asia/id Researches, three volumes of which had
come out; the footnotes in his paper show that he
read this new journal with profit. Its publisher, the
Asiatic Society in Calcutta, was modeled after the
Royal Society in London. Its founder was the
Orientalist William Jones, the youngest son of the
mathematician by that name, who had proposed
Lord Charles Cavendish for fellowship in the
Royal Society. The younger William Jones was said
to have understood Newton's Principia, and he was
in any case a Fellow of the Royal Society and a
good friend of Banks, Blagden, Phipps, and other
scientific men close to Cavendish." 17 Jones, who
himself had studied the Hindoo lunar year and
chronology, 10 * formed his "opinions of men and
things from evidence, which is the only solid basis of
civil, as experiment is of natural, know ledge." 104

There was a widespread interest in Hindoo
astronomy when Cavendish took up the subject.
William Marsden was an Oriental scholar who
published his researches in the journals of all of the
learned societies he belonged to, in the Asiatick
Researches, the Archaeo/ogia, and the Philosophical
Transactions. In the latter, in 1790, he published a
paper on the Hindoo year and calendar, in which
he remarked that Sanskrit scholars were making
possible "considerable discoveries in regard to the
scientific attainments of this ancient and
celebrated people," and that French astronomers
too had recently done important work on the
subject. Marsden attributed the attention to
Hindoo astronomy to its originality and probable
influence on the Greeks. 110 Samuel Davis, a civil
servant in Benares and one of the more scientifically
oriented members of the Asiatick Society, pub-
lished papers on Hindoo astronomy in the early

313

volumes of the Asiatick Researches. It was probably
through Davis that Cavendish came to make a
study of Hindoo almanacs. Davis had asked Banks
to show one of his papers to Cavendish, who made
comments on it and queried the author in 1791. 111
I Iindoo months depended solely on the motions of
the sun and moon, and so they had no definite
number of days and were not ordered by any cycle,
and moreover the month began on different days at
different latitudes and longitudes. This state of
affairs seemed chaotic to Cavendish, but Davis
assured him that three almanacs were commonly
used by the Hindoos and that they usually worked
fine for them. 112 Cavendish asked the Sanskrit
scholar Charles Wilkins, F.R.S., to lend him three
almanacs, which he then proceeded to work through
to decipher how the learned men of India knew the
date. Banks mentioned a possible membership in
the Royal Society to Davis, and in 1792, the year of
Cavendish's paper, Davis was elected; Cavendish's
name appears first on Davis's certificate. 113 The under-
lying reason for Cavendish's curiosity about Hindoo
astronomy was, we believe, the meaning it held for
his chosen life. On the other side of the world,
there were people like him who ordered their
existence according to the ways of nature.

In 1809 Cavendish published his last paper. He was
seventy-eight, and he had not published anything
for the past ten years. The subject in question was
close to his heart, astronomical instruments.

Instrument-makers had watchmakers to
thank for their dividing engines, the basis of

l05 Hcnry Cavendish, "On the Height," 235.

""■In 1790, clearly in response to a request by Cavendish, I lerschel
sent him his observations on two meteors in 17K4: William Herschel to
I lenry Cavendish, 1 Feb. 1790, ( lavendish Mss. New Correspondence.

""Garland Cannon. "Sir William Jones, Sir Joseph Banks, and
the Royal Society," Soles mitt Records of the Royal Society 29 (1975):
205-30, on 207-8.'

m R. Y. Subbarayappa, "Western Science in India up to the End
of the Nineteenth Century A.D.," in A Concise History of Science in
India, ed. D. M. Bose (New Delhi: Indian National Science
Academy, 1971 ). 484-97, on 495-96.

""Hans Aarsleff, the Study of Lang/tag in England. 17X0-1X60
(Minneapolis: University of Minnesota Press, 1983), 135.

""William Marsden, "On the Chronology of the Hindoos," /''/'
80 (1790): 560-84, on 560 .

"'Samuel Davis to Joseph Banks, 10 Mar. 1791. Banks
Correspondence. Kevv, 1.38.

" 2 Blagden forwarded to Cavendish Davis's answers to his
questions. Charles Blagden to Henry Cavendish, 7 Nov 1791. draft,
Blagden Letterbook. Royal Society, 7:579. Cavendish, "On the Civil
Year," 242.

"'Royal Society. Certificates. 5 (28 June 1792).

314

Cavendish

precision in eighteenth-century science." 4 Nothing
was so important to the success of instrument-
makers as the accurate division into equal parts of
the circles and parts of circles and straight lines of
their measuring instruments. Up to about 1740 the
divisions were always done by hand, a most delicate
procedure. John Bird, the master of hand dividing,
never let more than one other person into the room
when he was working, since the heat could spoil his
divisions. Reporting on the performance of a mural
quadrant divided by his method, Bird gave what
was the faith of an instrument-maker: "a mean of
sev eral observations, made by good observers with
accurate instruments, properly adjusted, will always
lead us either to the truth itself, or extremely near
to it." lis Jesse Ramsden made an excellent dividing
machine in the early 1770s using an endless screw
to turn a wheel under a cutting point, six revolutions
of the screw translating into one degree; the Board
of Longitude paid him to publish a description of
this engine. 116 When Ramsden completed his mural
quadrant for Milan in 1790, he invited Cavendish,
Aubert, Smeaton, who was another divider of instru-
ments, and others to see and try it. Ramsden told
them that "any common man in his workshop, with
good eyes and hands, could, on the same principles,
have divided it to equal perfection." 117 Ramsden
made it sound easy, but dividing w as the hardest part
of the instrument-maker's work. The instrument-
maker Edward Troughton stimulated Cavendish to
invent and publish his own method of dividing.

Edward Troughton and his older brother,
John, were renowned for their dividing instruments,
which were used by other instrument-makers, the
ultimate compliment. By the beginning of the
nineteenth century, Edward Troughton, who now
conducted the business alone, had succeeded
Ramsden as the foremost instrument-maker in
England. In 1807 Cavendish was one of a visitation
committee from the Royal Society who agreed with
the astronomer royal, Maskelyne, that greater
accuracy would be obtained if observations were
made with a circular instrument as well as w ith the
existing mural quadrant. The committee invited
Troughton to give a recommendation, which he
did, a circle six feet in diameter. The committee
and the council of the Royal Society approved the
recommendation, which was sent to the Board of

Ordnance. 118 In the following year, Troughton
delivered a paper to the Royal Society on his
method of dividing, for which he was awarded a
Copley Medal in 1809. 119 These events are the
setting of Cavendish's paper of that year.

Cavendish's purpose was to ease the "great
inconvenience and difficulty" of the common
method of dividing, which bruised the divisions by
laying the point of the beam compass in them.
Troughton had just published an alternative
"ingenious method," Cavendish said. By Cavendish's
method, the need to set the compass point in the
divisions was eliminated, and the "great objection to
the old method of div iding is entirely removed." It
was now up to instrument-makers to decide if his or
Troughton's method was best. 120 Cavendish's method
does not seem to have been adopted, but it nonethe-
less holds an interest for a biography of Cavendish.
This last publication of his was about a method for
improving the method of making the most precise
instruments of science; it was about the tools for
making the tools of science. Besides Troughton,
the only other instrument-maker named by Cavendish
in the paper was Bird, with whose observation
(above) he would have agreed: with accurate
instruments an accurate observer could arrive at
the truth or the closest thing to it. Cavendish's last
paper acknowledged the direction of science, to
which his earlier work had given such impetus.

"■•Maurice Daumas, "Precision of Measurement and Physical and
Chemical Research in the Eighteenth Century," in Scientific Change. . .,
ed. A. C. Crombic (New York: Basic Bonks. 1963), 418-30, on 422.

nl John Bird. The Method of Dividing Astronomical Instruments
(London. 1767). 13.

1 "'Jesse Ramsden. Description of nn Engine for Dividing
Mathematical Instruments ( I .ondon, 1 777).

" 7 Thesc are Blagdcn's words in reporting the inspection of
Ramsden \ quadrant to Sir Joseph Banks. Letter of 23 Sep. 1790, BI.
Add Mss 33272. pp. 89-90.

""Meeting of the committee on 22 Jan. and report of the
meeting of the council of the Royal Society on 28 May 1807,
"Visitations of Greenw ich Observatory 1763 to 1813." Royal Society,
Ms. 600. XIV.d.11, ff. 59-62.

"''A. W. Skempton and Joyce Brown. "John and Kdward
Troughton, Mathematical Instrument Makers," Notes and Records of
the Royal Society 27 (1973): 233-49, on 246. Roderick S. Webster,
"Troughton, Kdward," DSH 13: 470-71. Kdward Troughton, "An
Account of a Method of Dividing Astronomical and Other
Instruments by Ocular Inspection, in Which the Usual Tools for
Graduating Arc Not Kmployed. etc.." I'T 99 ( 1809): 105-45.

'-"Henry Cavendish, "On an Improvement in the Manner of
Div iding Astronomical Instruments," PT99 (1809): 221—45; Sci. Pap.
2:287-93. on 287.

CHAPTER 6

£arth

Triangulation

In 1783, Cavendish participated in an inter-
national survey, proposed by the French: a joint
determination of the relative positions of the na-
tional observatories in Paris and Greenwich (there
was an error of ten seconds in their longitudes).
Asked by the British government for his opinion of
the French proposal, Banks replied proudly that
the Royal Society had "people enough . . . capable
and willing." One of them was Cavendish, a skilled
surveyor and a conscientious servant of the Royal
Society, who could not have stayed away. The sur-
vey touched on a number of Cavendish's favorite
interests: e.g., the measurement of the heights of
mountains using a barometer;' precision of tech-
nique; and coordination of distant observers, an
aspect of standardization.

William Roy, a Fellow of the Royal Society,
was assigned responsibility for laying down the
triangles for the British half of the project. 2 Roy
brought considerable experience to this job: he
had made a military map of Scotland after the
Jacobite rebellion in 1 745, and after the Seven
Years War he had been involved in proposals to
make a map of all of Britain, but nothing came of
it. Then in 1783, after the American War, on his
own he began to make triangles in and around
London. 3 His chance to realize his goal of a
national survey came later that year with the
French proposal.

The initial step was to measure a base-line,
after which only angles needed to be taken to
determine the triangles. On 16 April 1784 Roy began
observations along a five-mile stretch of Hounslow-
Heath, near Greenwich, assisted by Banks, Blagden,
and Cavendish. Banks was enthusiastic; there morn-
ing to night, he opened his tents and offered refresh-
ments to all comers. Even the king came to look at
what was going on. By the end of the summer this
first phase of the triangulation was finished. 4

The next phase was to build triangles
twelve to eighteen miles on a side on a southward
course to the coast, to Dover, there to connect up
with the French triangulation from across the
channel. The ideal route would have been a
straight chain of equilateral triangles but the terrain
dictated a snake-like progression. 5 A French party
came to England, and Blagden crossed to France to
oversee the hookup of the triangles. Since at one
point Blagden spoke of Cavendish's plans to come
to Dover, Cavendish may have participated at the
end of the project as well as at the beginning. In
any event, it was finished in late 1 787/'

Cavendish's own locations at Hampstcad
and Clapham Common were used as corners in the
triangulation. He took bearings with respect to
every steeple and elevation in sight. His address
now had an astronomical reference.

The accuracy of the triangulation was a
point of honor, both professional and national. The
French had devised a method of repeated mea-

1 Theodore S. Fcldman, "Applied Mathematies and the
Quantification of Experimental Physics: The Example of Barometric
Hvpsomctry," Historical Studies in the Physical Sciences 15:2 (1988):
127-97, on 162.

^Joseph Banks to Charles Blagden, 13 Oct. 1783, draft, Blagden
Letters, Royal Society, B.19. Charles Coulston Oillispic, Science and
Polity in France at the End of the Old Regime (Princeton: Princeton
University Press, 1980), 122-23.

'William Roy, "An Account of the Measurement of a Base on
Hounslow-Heath," PT 75 (1785): 385-480, on 385-88. This earlier
work of Roy, beginning in 1 783. involved Banks. I [utton, and ! )eluc,
and it entailed measuring the heights of mountains (Shooter's Hill)
either by the barometer or by geometry. Joseph Banks to Charles
Hutton, n.d. /early 1784/, Wellcome Institute, MS 5270.

4 Charles Blagden to Joseph Banks, 12 July and " Tuesday" 1784,
Banks Correspondence, Kew, nos. 167, 171. Roy, "An Account of the
Measurement of a Base," 391, 425-26.

5 William Roy, "An Account of the Mode Proposed to Be
Followed in Determining the Relative Situation of the Royal
Observatories of Greenwich and Paris." /'7'77 (1787): 188-228.

'■Charles Blagden to Benjamin Thompson, 22 May 1787, draft.
Blagden Letterbook. Royal Society, 7:55. Charles Blagden to Henry
Cavendish, 16 Sep. 1787, Cavendish Mss X(b), 13. Charles Blagden
to William Watson, 27 Oct. 1787, draft, Blagden Letterbook, Royal
Society, 7:76.

316

Cavendish

surements chat enabled them to achieve high
accuracy with a modest instrument, a circle a foot
across. 7 The Fnglish achieved comparable accuracy
with a theodolite with a three-foot circle made by
Ramsden and paid for by the king. Blagden
described it as an "astonishing piece of workman-
ship, accurate to a degree hitherto wholly un-
exampled." 8 Roy carted this giant weighing two
hundred pounds into the field, where it stood, a
monument to the instrument-maker's precision.

Errors

Precision, however, is not only in the
instrument but also in the eye of the user and in the
hand of the calculator. Roy, a military engineer, took
great pride in his art, the supreme aim of which was
accuracy and precision. 1 ' Inforgiving when it came
to errors in calculations, in his 17X7 paper on the
planned trigonometrical operation in Britain, he
said that after bestowing "much care" on the
computations, he trusted that "no error of any
consequence will be found." That much any self-
respecting calculator might say, but Roy went
further, citing an error of his own, which he hoped
not to repeat: "Here it is proper that I should men-
tion a typical erratum in one of the tables of Trans-
actions, for 1777. It is Tab. VI . . . instead of 27.714
read 27.214."'" This venial error, a 2 in place of a 7,
was no doubt made in transcribing or typesetting.
Roy concluded his paper with a few corrections in
the tables, in a brief section of Errata. 11

But there were more errors in Roy's tables,
as he noted in his next paper on the subject, in
1790: "it is become necessary to take notice of
some mistakes that, through inadvertency, were
fallen into in the computed lengths of the arcs."
There w ere, in fact, "three kinds" of mistakes, and
at this stage all he could do was append a
correction slip to be pasted over the erroneous part
of the prev ious paper. 1 - Roy had a reputation for
painstaking work in a field that had no tolerance for
error: he regarded the triangulation project under
his direction as "infallible." 1 ' 1 It would seem to be a
case of the gods striking down one whom they
love. Roy's troubles had just begun. W hile prepar-
ing sheets of Roy's paper for the Philosophical Trans-
actions, Blagden discovered numerical "blunders,"
which he pointed out to Roy, who proceeded to
find more on his own. The paper in which he
corrected errors of his previous paper was itself full

of errors. Roy's health was now poor, and w hile he-
was absorbed in the melancholy task of discovering
and correcting his errors, on 1 July 1790 he
suddenly died at his house in London. 14

There were probably more errors buried in
the paper, and no doubt they would be
(triumphantly) discovered by the French
commissioners, especially P.F.A. Mechain, who was
bound to read the paper carefully. That was the
issue. Had Roy's errors been limited to the first
paper they would not have been damaging, since
that paper was only a sketch of the operation to
come. Krrors in the paper of 1790 were another
matter, for that paper was the final report of the
operation as carried out, an official undertaking of
the Royal Society. Blagden turned to the Royal
Society's learned member on the subject of errors.
"Conversing a few days ago on this subject with
Mr. Cavendish," Blagden told Banks, "he sug-
gested, that the best way of preventing any
disgrace which might fall upon the Society on this
account would be, to get the paper well examined
here, and print such errors as might be discovered
in the errata to the present volume of the
Transactions, thereby anticipating, as far as possible,
the remarks of foreigners." 15

Cavendish's proposal was one Roy himself
would have endorsed. At the time when the
French triangulation had been condemned as
"extremely erroneous," Roy had expressed confi-
dence that the Paris Academy of Sciences would,
"no doubt, vindicate the credit of their own
operations."" 1 To vindicate its own, the Royal
Society did what Cavendish recommended. Roy's
assistant, Isaac Dalby — in Roy's words, "an able

'Charles Blagden to Joseph Banks. 24 Sep. 17K7. BL Add Mss
33272, pp. 45-46.

"Charles Blagden to W illiam Watson. 22 Aug. 1787, draft. Blagden
Lcttcrbook. Royal Society. 7:347.

'Svcn Widmalm, "Accuracy, Rhetoric, and Technology: The
Paris-Greenwich Triangulation, I7K4-8K." in The Quantifying Spirit in
the Eighteenth Century, eds. T. Frangsmyr, J.L. 1 leilbron, and R.E. Rider
(Berkeley: University of California Press, 1990), 179-206, on 199.

"'Rov. "An Account of the Mode Proposed," 222.
"Ibid., 226.

'-William Roy. "An Account of the Trigonometrical Operation,
whereby the Distance between the Meridians of the Royal
Observatories of Greenwich and Paris Has Been Determined," PT
(1790): 1 1 1-270, on 201. Errata sheet follows p. 270.

l3 Roy, "Account of the Mode Proposed," 214.

l4 "Roy, William." DNB 17:371-7.?. on 373.

' s Charles Blagden to Sir Joseph Banks, draft, 31 Aug. 1790, BL
Add Mss 33272.

"'Roy. "An Account of the Mode Proposed," 21 1.

Earth

and indefatigable calculator" — was selected to
examine the paper for errors. Blagden reported to
Banks: "I have seen Mr Dalby, for the first time
this morning. He said there were to his knowledge
very many blunders retained by the General,
though clearly pointed out to him. Mr. Dalby
seemed doubtful whether it would look well in
him to be the detector; but I desired him to put
himself in the place of a foreigner, whose object it
might be to criticize as severely as possible, & that
we would then take care to present the result to
the public in the tendcrest manner for the
General's reputation, consistent with our duty to
the Society. He then undertook it ... " 17 Roy's
paper of 1 790 was corrected this way: in addition to
Roy's own errata for his previous paper of 1787, this
paper contained a second table of errata applying to
itself, as assembled by Dalby. To this now
posthumous paper, Blagden. also appended a brief
personal account of Roy, which offered a partial
excuse for Roy's lapses. Roy had finished the
triangulation in September 1 788, and he had spent
the next winter in Lisbon because of poor health.
He had hurriedly finished writing his paper on the
results of the triangulation before going to Lisbon,
and in the same month that he returned, in April
1 790, his paper went to press. He died before the
paper was completely printed, and although he had
corrected the sheets, he had not compared the
manuscript with the original observations. Errors
were found, with the result, Blagden said, that the
"General's friends, members of the Royal Society,"
had the whole paper revised by Dalby. IH Blagden
presented his appendix as an introduction to
another appendix by Dalby, in which Dalby went
through Roy's paper page by page, noting where
corrections belonged. w Errors haunted the project;
Dalby, in a paper the next year on measures
deducible from Roy's triangulation, noted yet
another error in Roy's 1790 paper, "which should
have been corrected in the Appendix." 20
Gavendish's house on Glapham Common had been
the corner of one of Roy's secondary triangles, and
in Roy's paper of 1790 its bearing eastward from
the meridian of the dome of St. Paul's was
printed — incorrectly. Dalby naturally wrote to
Cavendish about this error and corrected it in his
appendix. 21 The error might not seem like much:
instead of 26 degrees, 29 minutes, and 56.1 seconds,
it should have been 26 degrees, 29 minutes, and 52

seconds. But given the instruments, methods, and
abilities involved in the triangulation, it was an
inexcusable error. Ramsden's theodolite was accu-
rate to nearly one second, which was accordingly
the measure of scientific reputation and national
honor. To extricate the Royal Society from the
errors made in its name. Cavendish played his
familiar behind-the-scenes role as advisor. His recom-
mendation was candor: admit that mistakes were
made, find and fix them, and cut losses. In the
process of salvaging the reputation of the Society,
the reputation of Roy was protected as well; for
what was important about Roy's work was used and
saved, his observations. 11

Journeys

Active as he was in the planning of voyages
and expeditions approved by the Royal Society,
Cavendish, we have noted, never went on one of
these himself. I le did, however, make a number of
journeys by carriage, within Britain, always in the
summer when conditions of travel were at their best.
The first journey of which we have record was in late
August 1778, which took Cavendish through Oxford
to Birmingham and back by way of Towcester. At
each stop he made a trial of Nairne's dipping needle,
w hich is all we know about the trip and which may
have been the whole point. For it came soon after
Cavendish's report on the meteorological instruments
of the Royal Society, which included its earth-magnetic
instruments, and he was still very much involved in the
testing of meteorological instruments.-' Beginning in
1785 Cavendish became a regular and more rounded

"Blagden to Banks. 31 Aug. 1790.

'"Charles Blagden, "Appendix." to Roy, "An Account of the
Trigonometrical Operation." 591—92.

' 'Isaac Dalby, "Remarks on Major-General Roy's Account of
the Trigonometrical Operation, from Page 111 to Page 270. of This
Volume," I'T HO (1790): 593-614.

-'"Isaac Dalby, "'The Longitudes of Dunkirk and Paris from
Greenwich, Deduced from the Triangular Measurement in 1787.
1 7KK. Supposing the Earth to Be an Ellipsoid." /'/'HI (1791): 236-1.5.
on 24.5, note.

-'Letter from Isaac Dalby, undated, presumably to Cavendish,
in Cavendish Mss. Misc.

"Roy's errors were unimportant relative to his observations,
according to John Playfair. in his review of William Mudge's
collection of memoirs on the triangulation begun by Roy. in The
Works of John Playfair, ed. J. G. Playfair, 4 vols. (Edinburgh. 1X22)
4:181-220, on 198-201.

-''Henry Cavendish, " Trials of Nairne's Needle in Different
Parts of England," Cavendish Mss IX, 11:45-54. The usual place for
taking the trial was a garden. Dates in the second half of August 1778
are scattered through this record of observations.

318

Cavendish

scientific tourist. This fiftyish man of fixed, settled
habits had recently befriended Charles Blagden, who
had much to do with Cavendish's adventurous turn.

Blagden was an inveterate traveler. He was
also a compulsive note-taker and saver, who left us
a record, in the form of letters, of the journey he
took from London to Scotland, where he went to
study at age seventeen. The first letter begins: "As
I have often heard you mention how very
agreeable the acct of a journey is to you."- 4 Next
we have his report of a visit to Wales, when he was
twenty-three and an impressionable if conventional
tourist. He was a follower of Rousseau, - s drawn to
abbeys and vistas but also to mines and iron works
and "philosophical curiosities." His early observ ations
also reveal the accurate, scientific note-taker he-
was to become in Cavendish's company. Blagden
yearned to know the world, yet wherever he-
traveled he felt frustrated because people could
not answer his straightforward questions about
what lay a mile around them, places, routes,
departures, and the like. He was astonished at the
"stupidity of the people," who were entirelv
satisfied with their "little world."-''' (In this early
journal, a trait comes through, which would endure
and bring Blagden enemies: an air of superiority.) For
several years while a surgeon in the British army,
he observed as well as served in the New World. So
it was as a seasoned traveler that soon after his
return to Britain, he toured Devonshire, where he
found the coves and rocks "beautiful" and "roman-
tic," but where he also observed mileages, weather,
slate, and clay.- 7 His most memorable journey, as it
turned out, was from Plymouth to London, where
he would make his life in science. ZH In the summer
of 17H3 Blagden v isited France, but by then he was
already in the serv ice of Cavendish. 29

Blagden urged Cavendish to take up
traveling with him. In the first of his many letters
to John Michell, in 1785, Blagden wrote that he
"endeavoured to persuade our friend Mr
Cavendish to make you a visit at Thornhill," so far
in vain. 30 Blagden told Michell that he did not want
to come alone but he hoped that he and Cav endish
could come next year/' which they did. For this
year they were going in another direction, to south
Wales, and Blagden had made advance arrange-
ments: the plans were set; Blagden wanted to see
the industrial landscape, and so did Cavendish.
Blagden wrote to William Lewis that he had

proposed to Cavendish that they visit his iron works
in Glamorganshire and that Cavendish was "very
curious." Lewis wrote back that they could stay at
his house or if the "Hammers should be too noisy"
at another, distant house.'- They left on a three-
week trip. Cavendish taking with him one servant."
Along the w ay they talked to the owners of works,
engineers, agents, and workmen, who told them
things no one else could. At Glamorganshire
Cavendish visited not only the iron works but a
spring that gave off bubbles, which he tested. 54
Midway into their journey Blagden could tell Banks
that Cavendish "bears the journey remarkably
well." 55 In Wales they v isited the iron and the cloth
manufacturers. Lewis became another scientific
outpost for Cavendish; for years after this visit,
Lewis sent him specimens, especially of kish (a
kind of graphite that separates from iron in
smelting), for Cavendish to examine. 36 The sixty-
two-page journal kept of this trip shows that the
main purpose of it was to learn about industry.

Their tour was by no means original. That
same year, for example, the London chemist
William Higgins visited the English factories."

-' 4 Charlcs Blagden to Sarah Nclmcs, 1 Nov. 17f>5. Blagden
Letters, Royal Society. B.1S9. The next letter. B. 160, continues the
account of that journey. In other letters in 17i>7 Blagden gav e Nclmcs
aeeotints of shorter journeys in Scotland. Nclmcs, w ho liv ed in Bristol,
and Blagden were distant relatives. "Accounts. Bills, Insurance, and
( :<ipy of Will of S. Nclmcs," Blagden Mss. Royal Society.

a To a friend Blagden recommended that he read Rousseau,
"the most eloquent is: feeling of men." Charles Blagden to Thomas
Curtis. 26 July 1771, Blagden Letters, Royal Society, B.162.

-''■Charles Blagden, "Memorandum of a Tour Taken for Lour
Days Beginning Aug. 18 1771." Blagden Papers, Yale, box I, folder .V

-'Charles Blagden. " Lour of the South Hams of Devonshire."
1 780, Blagden Diaries, Yale. Osborne Shelves f c 16.

-'"Charles Blagden. "Journey from Plymouth to London 1781,"
Yale, Osborne Shelves f c 16.

-''Charles Blagden, memoranda of his trip to Prance in 1785,
Blagden Papers. Vale, box I, folder .V

"'Charles Blagden to John Michell, 25 Apr. 1785, draft, Blagden
Letterbook, Yale.

"Charles Blagden to John Michell, 13 Sep. 1785, draft. Blagden
Letterbook. Yale.

"Charles Blagden to William Lewis. 20 June 1785, draft,
Blagden Letterbook. Yale. William Lewis to Charles Blagden. 25
June 1785, draft. Blagden Letters. Royal Society. L.46.

"Blagden was undecided if he wotdd bring his servant too.
Bladgen to Lewis. 20 June 1785.

"Charles Blagden to Joseph Banks, 9 Oct. 1785, Banks
Correspondence. Kew. 1.210.

"Charles Blagden to Joseph Banks, .si July 1785, Blagden
Correspondence. Kew, 1.199.

"■Charles Blagden to William Lew is. 10 Nov. I78fi, f> Nov. 1787,
drafts, Blagden Letterbook. Royal Society. 7:55 and 7:85.

,7 A.E. Musson and L. Robinson, Science mid Technology in the
Industrial Revolution (Toronto: I nivcrsitv of Toronto Press. 1969), 122.

Earth

This kind of sightseeing had been going on; fifteen
years earlier, Benjamin Franklin had visited the
manufacturing towns of England. At the Soho
Works outside Birmingham, Matthew Boulton
showed machines to scientists and manufacturers,
even ambassadors and princes. ,x The conventional
beginning of the British industrial revolution is 1760,
the year Cavendish entered the Royal Society. His
scientific work was carried out in the time of this
great technical and social transformation, which
could not fail to interest him. By the time of his
journeys with Blagden, twenty-five years later, an
extraordinary industrial landscape was coming into
being. Cavendish ventured into it with all the
curiosity he brought to his studies in heat and air. In
the same period, science in Britain had begun to
flourish in" the industrial provinces and was no
longer primarily located in the metropolis. On this
first journey, after Wales, Cavendish went to
Birmingham, where the Lunar Society had been
meeting since the late 1760s. This scientific and
technical society included James Watt, Joseph
Priestley, Joseph Black, James Keir, Josiah
Wedgwood, and other prominent scientific and
industrial men. Manchester and other provincial
towns were acquiring their scientific and literary
societies. Cavendish might seem to be carrying
coals to Newcastle, but his purpose in touring the
industrial provinces was to learn firsthand about
this new way of mastering nature.

Cavendish and Blagden observed quarries,
cloth manufacture, especially dying, coal mining,
coal-tar manufacture, lime kilns, coke-making,
copper-casting, brass-drawing, and, above all, iron-
making. They saw iron and steel being made for
buttons, needles, nails, and ship bolts. They saw
slitting and flatting mills, hammers, rollers, cranes,
pincers, and other heavy machinery, and enormous
iron furnaces, standing as high as forty-five feet. It
was spectacular: the scenes at the forges were
violent with their intense heat and fireworks, and
coal pits burned. Yet there was an unmistakable
similarity between this landscape and Cavendish's
serene laboratory. The manufacturers used the
same chemicals he did, such as spirit of salt, only
they used them in vast quantity. The hearth, the
bellows, the concern with impurities, and the
bringing together of materials by proportionate-
weights were all familiar to Cavendish. He and
Blagden brought with them a collection of

instruments including chemical equipment, and they
even tried their own little experiment on tin in acid. 39
In Birmingham, they saw Watt and the
industrialist John Wilkinson. Watt had made his
greatest improvement in the steam engine, the
separate condenser, in the 1760s, but he had made
another important one in 1782, just three years
before Cavendish's visit. This one converted the
linear motion of the piston's drive to a rotary
motion, useful in mills, and Cavendish saw this
latest improvement. Early that year, when Watt
was in London, he dined with Cavendish at the
Royal Society Club. 40 In Birmingham Cavendish
called on Watt, now just over a year after the water
controversy and Watt's private denunciations of
Cavendish. The journal gives no hint that there
was any barrier between the two men or that they
talked about the composition of water. They surely
talked about machines. Watt showed them a
machine for making plate, invented and patented
by another man but claimed by Watt as his original
idea. Watt described scientific experiments he had
done with the steam engine on the condensation of
steam, complete with an explanation of the
"latent" heat evolved: the latent heat of steam was
948 degrees Fahrenheit, he told Cavendish (who
had found 982 degrees). Watt showed them a
furnace he had contrived for burning smoke, which
he intended to apply to the steam engine. At other
iron works, Cavendish and Blagden came across
more of Watt's steam engines in use. 41 Cavendish
was intrigued by Watt's inventions; in the journal of
the visit, there is a drawing by him of the rotative
mechanism for the steam engine, and in his papers
there is a drawing of Watt's smoke-burning
furnace. 42 That fall Watt came to London to Albion
Mills at Black Friars Bridge, where his new smoke-
burning furnaces were to be installed, and we can
be sure that Cavendish was on hand. 4 '

'"Robert K. Schofield. The I .unar Society oj Kinninghtim: .1 Sor'uil
History of Provincial Science and Industry in Eighteenth-Century England
(Oxford: Oxford University Press, 1963), 26-27, 113.

'' The journal is in a wrapper labeled in Cavendish's band.
"Computations & Observations in Journey I7KS," Cavendish Mss
X(a). 4. The journal itself is in another hand.

«It was on 24 Feb. 1785. Archibald (ieikie. Annuls of the Royal
Society Club (London: Macmillan, 1917), 174.

41 "Computations is: Observations in Journey 1 785."

^Henry Cavendish. "Watts Fire Place for Burninf; Smoke."
Cavendish Mss. Misc.

4, Charles Blagden to Sir Joseph Banks. 23 Oct. I7KS, Banks
Correspondence. Kew. 1.212.

320

Cavendish

On this their first journey together, Cavendish
and Blagden earried out studies in Cavendish's well
established interests: heats of wells, heights of
mountains by the barometer, and measures of tides.
There is also a new active interest, geology. Cavendish
and Blagden made regular observations of strata
and the rocks on the surface and the pebbles
surfacing the roads, noting color, texture, and lay.
They saw blue, red, and white clay and limestone,
granite, sand, slate, and so on. They drew no
conclusions but no discouragement either; they
continued to make geological observations on all of
their subsequent journeys. 44

In the early summer of the following year,
1 786, Blagden 's brother, John Blagden Hale, in-
vited Cav endish to join Blagden on a visit. Blagden
told his brother that he had "every reason to believ e
that he /Cavendish/ will not find it convenient to
go from home." Blagden conveyed the invitation,
but he knew his friend. A week later he w rote to
his brother to confirm that Cavendish did "not find
it convenient to leave home . . . " 45 He added "at
this time": two months later Cavendish and
Blagden set out again on a roughly three-week trip,
this one much longer than the first, over eight
hundred miles to the north of Kngland and back. It
was the trip Blagden had wanted to make the year
before, to see John Michel! at Thornhill, near
Wakefield. They went directly to Michell's, 4 '' then
to John Phipps, now Lord Mulgrave (to whom
Cavendish gave scientific instructions on his
voyage to the north), then to the Lake District, and
then back to Michell's where they staved six
days. 4 ' In the journal of this trip, there is no
mention of Michell's experiment on weighing the
world, which he still had not got around to doing.
The main attraction was Michell's great telescope,
which was spectacular but disappointing, since
Michel! had cracked the speculum; although he had
ground and polished it again, it was imperfect.* In
his diary, Blagden wrote:

At Mr Michell's took some altitudes is: looked over
his fossils . . . At night looked thro' his telescope:
tho' much false light is; confused images yet obs'd
/Saturn/ with it well: could see the belt plainly; &
obs'd an emersion of the 3 sat. much better than it
appeared thro' the 2 feet reflector. 4 ''

Blagden went to Michell's sermon on Sunday,
w hich he had heard or read before. Most of his and
Cavendish's time seemed to have been spent
making — rather wanting to make, since the

weather was foul — excursions up mountains with
Cavendish's barometer, "a main object" of their
tour. 50 They came away from Michell's with one
treasure: Michell's table of strata, their depths
measured to the inch, down to 221 feet. 51
Cavendish's account of this journey is mostly about
strata. 5 - He discussed geology with Michell,
Michell's particular field, and after this visit he
corresponded with Michell about geology. 53
Michell was a stimulus to Cavendish in geology as
he was in other subjects. Michell was one of the
new geologists who brought together theory and
field work, which had been separated in the past.
Cavendish was one of the new geologists too by
virtue of his journeys; in Britain the main spur to
geology in the late eighteenth century was
precisely what he was doing, crossing large tracks
of country making observ ations of strata. 54

Cavendish and Blagden took in other things on this
trip. They toured an alum works near Lord
Mulgrave's. 55 They went to an iron works in
Rotheram, from w hich Cavendish brought home a
chunk of kishy iron to examine. In Sheffield they
observed file-making and other manufactures

M "Computations & Observations in Journey 17K.S." Cavendish
Mss. Misc. contain many pages of data from this trip. Cavendish and
Hi dden used a Dudley's quadrant borrowed from Aubcrt. and they
made a long series of elevations taken by the barometer and
corrected by the thermometer. They brought their journev to an end
with readings in Cavendish's library at Bedford Square on their
return to London on August 8.

4S Charles Blagden to his brother. John Blagden Hale. 13 and 20
June 1 7K6. drafts. Blagden Letterbook, Royal Society. 7:4 and K.

'"Charles Blagden to Lord Mulgrave, 2 Aug. 17Kb, draft,
Blagden Letterbook. Royal Society, 7:17. Charles Blagden to John
Michell. 5 Aug. 17K6. draft, ibid., 7:21.

"Charles Blagden to his brother. 14 Sep. 1786. draft. Blagden
Letterbook, Royal Society. 7:33.

"Charles Blagden to Sir |oscph Banks. 1° Ann. 1786, BL Add
Mss 33272.

w Encry for 2 Sep. 17Kf>, Blagden Diary, Yale, Osborn Shelves fc 16.
""Charles Blagden to Sir Joseph Banks. 13 Aug. 17Kb. BL Add
Mss 33272, p. I.

51 Henry Cavendish, "Strata Which Michell Dug Through for
Coal." in Cavendish's journal of the 17Kb trip. Cavendish Mss X(a),
3:13-14. In Michell's table there are thirty levels, coal alternating
with various other matter. Down to 77 feet it gave Michell's own
know ledge: the rest came from pits.

^-Cavendish's journal of the journev of 17Kb, Cavendish
Mss X(a), 3.

"Henry Cavendish to John Michell. n.d. /1 7X7/, drafr.
Cavendish Mss. Misc. John Michell to llenrv Cavendish. 14 Aug.
1788, Cavendish Mss X(b), 15.

54 Roy Porter. The Making oj Geology: Earth Science in Britain,
1660-/X/5 (Cambridge: Cambridge University Press, 1977). 1 19.

""Computations cv Observations in Journey 17Kb." Cavendish
Mss X(a), 5. The wrapper is labeled in Cavendish's hand, the
narrativ e in another.

b.dith

"pretty much in detail." and they stayed at an inn
recommended by Michell ("the vilest house,"
Blagden complained to Michell, "at which I had
ever the misfortune to put up"). 56 In Chesterfield
they went down the mines; Blagden found the
ladders "fatiguing" and his legs too short, but he
said nothing of Cavendish's discomfort, if any.
Cavendish was interested in the mine and the
evidence of violence in it, which led him to think
that there had been an explosion." "Tempestuous"
wind and rain frustrated their plans to climb
mountains in the Lake District, and they left
sooner than they had planned, but not before
Blagden had caught a glimpse of the "magnificent
& beautiful" scene. sx What Cavendish thought of
it he did not say or Blagden did not record. (The
closest Blagden came to a criticism of Cavendish
was in connection with this trip to the Lake
District; to a friend fifteen years later, Blagden
wrote, "When I went to the lakes it was in
company with Mr Cavendish, who had no curiosity
for several things which it would have given me
great pleasure to have seen." 59 ) A month after
their return to London, Blagden wrote to Banks
that Cavendish was "making experiments upon the
stones we brought home," especially specimens
from the iron and alum works/' 0

For the third straight year, in 1787,
Cavendish and Blagden set off on a journey of
about three weeks, now to the southwestern corner
of England, Cornwall. As before, long in advance
Blagden made arrangements for them to be met
and shown the sights along the way. Their route
was planned so that Cavendish always saw
something new by traveling a new road. 61 Blagden
had solicited letters of recommendation identifying
them and giving their purpose, "a philosophical
tour." 62 James Watt and his partner Matthew
Boulton supplied them with letters to admit them
to mines, for example. 63 The famous mines of
Cornwall being new to both Cavendish and
Blagden/' 4 they went down one, a tin mine a
hundred fathoms deep. Blagden found the descent
troublesome and uninteresting because he could
not see anything, and Cavendish may have too,
since on the rest of the trip they contented
themselves with seeing what was above ground/' 5
This included tin and copper mines and Josiah
Wedgwood's clay pits for his porcelain
manufacture. The travelers were already in touch

with Wedgwood, who in the previous winter had
sent Blagden a number of specimens of minerals
with the request that he show them to Cavendish
and Kirwan. They were mainly specimens of
feldspar (he called it feltspat), which of course were
of interest to him as a manufacturer of pottery (clay
originating mainly in the decomposition of
felspathic rocks). Wedgwood was an industrialist
who looked to experimental chemistry and heat to
advance technology, in his case ceramic; he was
exactly the kind of person Cavendish liked to
associate with, and these journey gave him plenty
of opportunity/''' Cavendish and Blagden observed
the smelters w ith their strong smell of arsenic and
the workmen covered with red dust. They saw the
great stampers driven by waterwheels, crushing the
ore, and steam engines everywhere, emptying the
mine shafts of water and hauling up the ore/' 7
They saw the pumping machinery improved by
Watt, to whom, Blagden thought, the Cornish were
indebted to be able to "work their copper mines at
all." 68 As before, Cavendish returned home with
specimens of all kinds of ore to subject to "chemical
analysis," which Blagden expected would "shew

■"■Charles Blagden to John Michell. 1" Sep. 17X6. draft, Blagden
Letterhook. Roval Society, 7:37.

5'Charles Bladen to Sir Joseph Banks. 17 Sep. 17X6. BL Add
Mss 33272, pp. 9-10.

-Charles Blagden to Sir Joseph Banks. 4 Sep. 17X6. BL Add
Mss 33272. pp. 7-8.

^"Charles Blagden to Lord Palmerston, 2.5 Nov. 1X00. Blagden
Letters. Yale.

'■"Charles Blagden to Joseph Banks. X Oct. 17X6. BM Add
Mss 33272.

61 Blagden explained that they would take a route to Cornwall
along the sea because of "particular experiments" to be done there,
and they would probably not accept an invitation from Bristol
because Cavendish had been there and would "wish CO return by a
new road." Charles Blagden to William Lewis, II July 17X7. draft.
Blagden I.cttcrbook. Royal Society. 7:338.

''-'Two letters from George I luni /?/. 23 Jan. 1 7X7, who was asked
to write letters of introduction by his nephew R Wilbraham, "The
bearer of this are Mr Cavendish . . ." Blagden Papers. Yale, box 1.
folder 4. Along the way, too. Blagden solicited letters, such as James
Rennell to Rev Burington, IX Aug. 17X7. "The bearer. I)r Blagden.
is my particular friend ..." Blagden Letters. Royal Society. R.5.

"Charles Blagden to James Watt, 23 Aug. 17X7, Blagden
Letterhook, Royal Society. 7:349.

'-'Charles Blagden to Mrs. Grey, 14 June 17X7. Blagden
Letterhook, Royal Society, 7:324.

"Charles Blagden to William Watson, 22 Aug. 17X7. Blagden
Letterhook. Royal Society, 7:347.

"Josiah Wedgwood to Charles Blagden. 30 Dec. 17X6,
Gloucestershire Record Office, I) 10X6, F LSX.

''Thirty-page journal of the 17X7 journey in another's
handwriting but with many insertions in Cavendish's hand.
Cavendish Mss X(a). 6.

"Charles Blagden to Mrs. Grey, 2X Aug. 1787, draft. Blagden
Letterhook. Royal Society, 7:351.

322

Cavendish

some more light upon their origin."'' 1 ' Their
industrial tour was at the same time a geological
and mineralogical tour; Cavendish's own notes on
the journey between industrial sites were mainly of
observations of strata. 7 " The weather favored them
on this journey, enabling them to go up mountains
with their barometer to measure heights. 71 They
kept busy and happy, and Blagden thought that
Cavendish looked "the better for his journey." 72

Independently of their industrial sightseeing
in Cornwall, Cavendish and Blagden made a side
trip to Dartmoor, there to earry out an elaborate
experiment on the heights of mountains, planned
long in advance. Ever since Pascal sent his brother-
in-law up a mountain with a barometer in 1648, the
prospect of measuring the heights of scalable
mountains barometrically was recognized as an
alternative to trigonometrical methods. During his
first year in the Royal Society, Lord Charles
Cavendish, for example, heard a report on a method
for finding heights by the barometer. 73 Henry
Cavendish's associates had recently gone to Mont
Blanc to make measurements by a combination of
barometry and trigonometry. In the 1770s, first Jean
Andre Deluc and then Ccorge Shuckburgh, a
specialist in instruments and weights and measures,
published the observations they had taken on Mont
Blanc; they made a case for Mont Blanc being
Europe's highest peak, and they also disagreed
about heights. 74 Traveling through the Alps with
his "portable philosophical cabinet," Shuckburgh
repeated Deluc's experiments using Deluc's "rule"
for correcting the barometer for temperature, and
he got yet different results. In that decade, other of
Cavendish's associates, Nevil Maskelyne, Samuel
I Iorsley, and William Roy, still published on the
heights of mountains as measured by barometers.
Shuckburgh and Roy devised variant "rules" of
their own in the belief that if the right rule were
found, the method would be accurate enough to
become practical; as Shuckburgh said in 1777, the
long-known and rarely practiced method of taking
heights with the barometer had been "capable of
but little precision till within these few years." 75
With the new researches from the 1770s,
stimulated especially by Deluc, the method did
become both reasonably practical and exact. 76
Cavendish's work on it was a continuation of his
work in meteorology; he compared the competing
rules for correcting the barometer for temperature,

drawing on his father's experiments. 77 He assisted
Roy in experiments on the expansion of mercury in
connection with measuring the heights of mountains,
again drawing on his father's work.™ Like Roy,
Cavendish did not go to that three-mile high
mountain, Mont Blanc, but was satisfied to do
computations on it at home, using the barometer
and thermometer readings taken by Deluc and
Shuckburgh; 79 Cavendish, too, arrived at different
results for the height.* 0 At just about this time,
Mont Blanc was scaled for the first time, in 1786,
by Michel Gabriel Paccard. It was a bold climb,
made with only one porter, and since many attempts
by others had failed, this one was especially stir-
ring. Paccard had taken a barometer with him, not
to advance science but his nation; he wanted to
prove that his mountain was the highest in
Europe.* 1 The next year, 1787, his ambitious
countryman Horace Benedict dc Saussure led a
party of twenty up the mountain to return with a
treasure of scientific observations. The results of
Saussure 's barometric readings on that climb were
published only in 1796, in a volume of his Voyages
dans les A/pes, sz but the feat was widely publicized

"Charles Blagden to John Michel), 11 Sep. 1787, draft, Bladen
Letterbook, Royal Society. 7:354.

711 1 lenry C lavendish's journal of the 1 787 trip. Cavendish Mss X(a), 7.

"There are several large sheets of observations taken with the
barometer on the 17K7 trip in Cavendish Mss, Misc.

-Charles Bladen to Sir Joseph Banks, 14 Aug. 1787, Bl. Add
Mss 33272.

7l J. G. Scheuchzer's paper on the subject was read on 8 Feb.
1727/28, Royal Society, J B 13:173.

;j Gavin de Beer, " The I listory of the Altimetry of Mont Blanc,"
Annals of Science 12 (1956): 3-29, on 3-4.

"George Shuckburgh, Observations Marie in Savoy, in Order to
Ascertain the Height of Mountains fry Means of the Barometer, Being an
Examination of Mr De Luc's Rules, Delivered in His Recherches sur les
Modifications de I' Atmosphere. Read at the Royal Society. May K and 15,
1777 (London. 1777), 1-2, 12-13.

"Teldman, "Applied Mathematics and the Quantification of
Experimental Physics," 151. 177-78.

"Comparing rules by Deluc, Bougucr. and Maskelyne,
Cavendish referred to his father's experiments on the specific gravity
of air at given temperatures and pressures. Henry Cavendish, "Rule
for Taking Heights of Barometers," Cavendish Mss VIII, 12.

""William Roy. "Experiments and Observations Made in Britain,
in Order to Obtain a Rule for Measuring Heights with the
Barometer." PT 67 (1778): 653-788, on 673.

''Henry Cavendish, "Observations of Thcrmom on Mont
Blank," in Cavendish Mss, Misc.

""Charles Blagden to Sir Joseph Banks, 5 Oct. 1786, BL Add Mss
33272, pp. 19-20. Cavendish's calculation of the summit of Mont Blanc.
Blagden reported, came out lower than Shuckburgh 's by 700 feet.

"'Charles Blagden to Mrs. Grey, 5 Oct. 1786, draft, Blagden
Letterbook, Royal Society, 7:39. T. Graham Brown and Gavin de
Beer, The First Ascent of Mont Blanc (London: Oxford University
Press, 1957), v, 3.

"2De Beer, "History," 22.

Earth

at the time. That was the year of Cavendish and
Blagden's journey to Dartmoor, to Cavendish's
mountain, only a few hundred feet high.

In an earlier volume of Saussure's Voyages, pub-
lished in 1 786, 8 ^ he gave observations on Mont Blane
but not yet from the top. It was this account that
suggested to ( iavendish the idea for the experiment
on Dartmoor. Twice, two days apart, Saussure
measured the elevation of one station on the moun-
tain over another and obtained different results, a
discrepancy of nearly two percent. Even more
puzzling was the effect of the temperature correc-
tion on the barometer reading: instead of making
the two measurements more consistent, it made
them less so. Saussure concluded that an important
consideration was being overlooked in the measure-
ment of mountains; namely, variations of the barom-
eter over time were proportionately less on the
mountain than they were on the plain. There was
no known reason why they should not be
proportional, but there it was, and it pointed to the
need for a correction to a (temperature) correction in
the barometric measurement of heights. To show
what he meant, Saussure gave an example: high up
on a mountain where the mean reading of the
barometer was only 7/8 or 3/4 of what it was at sea
level, the barometric variations about the mean
reading should also be 7/8 or 3/4 of the variations at
sea level, but experiment showed that the variations
were proportionately much less above than below.
Daniel Bernoulli had observed this fact long before
and had postulated heavy exhalations in the air that
did not rise to higher elevations. Deluc had
recognized irregularities in the variations, but he
did not consider any corrections other than those for
heat and humidity. Saussure proposed the existence
of a correction of an "absolutely different genre."
The solution to the problem of determining
heights by the barometer was not the construction
of corrective scales and tables but research into the
"law of variations." It was "in effect one of the most
interesting problems of meteorology," Saussure
wrote, and he called for new observations at
different heights and in very different states of the
atmosphere. 84 The barometric measurement of the
heights of mountains pointed to a fundamental
problem of the atmosphere.

Cavendish responded by arranging for a
long series of observations using barometers, ther-

mometers, and rain gauges at the top and bottom
of Dartmoor. The project was conceived, planned,
and funded by Cavendish.

Dartmoor was close to Plymouth, where
Blagden had lived before coming to London. He
made the local arrangements, which called for three
men to assist in the experiment. 85 The one in charge
at the site was William Farr, a long-time friend of
Blagden and physician at the royal naval hospital near
Plymouth. 86 Farr was a graduate of Edinburgh, where
he wrote his dissertation on the uses of mathematics
and natural philosophy in the study of medicine. A
Fellow of the Royal Society, Farr regularly published
his meteorological journals from Plymouth in the
Philosophical Transactions. These journals recorded
that he took readings twice a day, precisely at 9 a.m.
and 11 p.m.; he was an observer who could be
counted on. 87 The lower of the two meteorological
stations on Dartmoor was Thomas Vivian's house.
The higher station had to be built by V ivian and Farr,
who made it solid enough to be secure "both from
storms & ill-disposed persons." Cavendish ordered
instruments for Vivian's house and the new building
and sent them ahead with instructions. He hired a
third helper, R. Wilson, to read the "small very
sensitive ther." and other instruments three times a
day. 88 The setting-up of the experiment was to be
done by Cavendish himself, and on IS July 1787
Cavendish and Blagden left London for Plymouth to
arrive at about the same time as the instruments. The
exact difference in elevation of the two stations had to
be known (it was roughly a thousand feet), and to this
end, in a heavy rain, the parry struggled up the moor
with their leveling instruments. 89

"'Charles Blagden to John Michcll. 11 Sep. 1787, draft. Blagden
Letterbook, Royal Society. 7:354.

"■•Horace Benedict de Saussure, Voyages dans les Alpes, precedes
d'un essai sur l"histoire naturtlle des environs de Ceneve (Geneva, 1 786).
575-78, 581-82.

85 Blagden also traveled in the region around Dartmoor. Relative
to an observation near Dartmoor. Cavendish wrote in his account in
1787 that "Dr HI. in a former journey was informed ..." Cavendish's
journal of his 1787 trip. Cavendish MssX(a). 7.

Wl Letters about family and work from William Farr to Blagden, 27
Apr. 1781 and 3 Nov. 1782', Blagden Letters. Royal Society, F.2 and K.V

"'William Farr, "Observations on the Barometer and Thermometer,
and Account of the Whole Rain in Every Month of the Year 1767.
Taken at the Royal Hospital Near Plymouth." I'T 58 (1769): 136-39;
"Abstract from a Meteorological Register Kept at the Royal 1 lospital
Near Plymouth, During the Year 1768," PT 59 (1769): 81-85.

""Charles Blagden to William Farr. 12 June and 3 July 1787,
drafts. Blagden Letterbook, Royal Society. 7:67 and 7:335.

"'Charles Blagden to William Farr, 3 July 1787. From the
bottom of the sill of V ivian's door to a pencil mark on the post of the

324

Cavendish

It soon became clear that their effort had
been in vain. On the point raised by Saussure, the
experiment proved inconclusive, probably because
Dartmoor was not Mont Blanc: the difference in
elevation of the two stations was too small to
register the effect. Blagden described to Michell
their meager consolation: the experiment showed
something about the value of comparing barom-
eters and of comparing rain at the top and the
bottom of a hill,'"' and Cavendish had estimated
the height of the highest part of the local hills.'"
Correspondence passed between Plymouth and
London about the readings with the rain gauge, 1 '-
and then the correspondence turned to practical
matters of bringing the experiment to a close. 93 In
early 17S9, a year and a half after the experiment
had begun, Blagden wrote to Farr in Plymouth
mentioning the king's madness but nothing about
the experiment.'' 4 But the experiment had been care-
fully executed, and it had theoretical significance.
Through it Cavendish revealed his administrative
skills as a scientific director with Blagden's
indispensable help. This scientific expedition into
the wet and windy moors had taken the coordi-
nated efforts of four men, in addition to Caven-
dish's own.

On Dartmoor Cavendish had his scientific
staff, but for most of his other distant geological
information, he relied solely upon Blagden, who for
three years in succession, 1787-89, journeyed
without Cavendish to France. In the same year as
the experiment on Dartmoor, Blagden sent
Cavendish observations from France on strata with
the clear intention of connecting them with their
observations of English strata.'' 5 In the summer of
1788, Blagden observed that the soils in France
were similar to England's. 96 In the fall of 1789
Blagden was back in France, from where he made
an extended trip into western Germany, making
notes of strata all the w ay. 1 ' 7

Cavendish made one more journey, this
time on his own, in 1793, w hen he was nearly sixty-
two. Blagden was then living in Europe and in cor-
respondence with Cavendish. 98 Cavendish traveled
north from London as far as Derbyshire and
Lincolnshire, stopping at quarries and collieries, and
noting the strata. The purpose of this trip would
seem to be Watt. Using his steam engine as a
scientific instrument. Watt measured the specific-
gravity of steam, an experiment w hich Cavendish

entered in his journal of the trip. Cavendish
witnessed trials of Watt and Boulton's steam
engines in Birmingham, and it seems that Banks
took Blagden's place in encouraging Cavendish to
be there, as he himself intended to be. 99

Such were Cavendish's purposes in his
journeys outside London. These journeys were
active. He examined industrial processes and their
materials and products; he determined the heights
of mountains; he collected "stones," noting their
physical descriptions, and, often, dissolving them in
acids;"" 1 and he observed the "order of the strata." 101

Cavendish had the same interests as his
geological colleagues: mountains, strata, and
minerals. Saussure said of his alpine voyages that
once he had enough facts about high mountains, he
would have the foundation for some general

meteorological hut on top of Dartmoor, they measured 958 63/1011
feet. The distances from the bottom of the sill to the bottom of the
cistern of Vivian's barometer, and from the pencil mark on the post
to the bottom of the cistern of the barometer in the hut, they left for
Wilson to measure. Charles Blagden to William Fair, 22 Auk- 1787.
draft. Blagden l.etterbook. Royal Society. 7:346.
'"'Blagden to Michell. 11 Sep. 1787.

"Blagden to Watson. ZZ Ann. 1787. Charles Blagden to Mrs.
Grey, 28 Aug. 1787. draft. Blagden l.etterbook. Royal Society, 7:351.

,2 Judging from Farr's observations. Cavendish suspected an
irregularity in Sisson's glass rain tube. Charles Blagden to William
Farr. 5 Dec. 17X7 and 8 Jan. 1788. drafts. Blagden l.etterbook. Royal
Society. 7:43 and 7:103. Farr promised to correct any mistake in the
register. William Farr to Henry Cav endish. Mar. Z /1788/, Cavendish
\lss. New Correspondence.

"Cavendish offered to let Vivian keep the instruments at his
house. I le told l-'arr to give the instruments in the hut to anyone w ho
could use them or else to return them. Cavendish had intended for
Wilson to keep the register only until the end of 1787, but he
continued on at Cavendish's expense and under Farr's direction.
Charles Blagden to William Farr. 25 Oct. 17XX. draft, Blagden
l.etterbook. Royal Society. 7:168. Vivian thanked Cavendish for the
instruments and for the expense and trouble in "promoting
philosophical knowledge by experiments in the neighborhood."
Thomas V ivian to Henry Cavendish. 26 Nov. 1788, Cavendish Mss.
New ( lorrespondencc.

"H :harles Blagden to William Farr. 24 Jan. I 7X9, draft, Blagden
l.etterbook. Royal Society. 7:206.

'"The notes of Blagden's journey in France in 1787 are in
Cavendish's handwriting. Cavendish Mss \(a). I.

"Charles Blagden to Joseph Banks. 13 July 1788. .BL Add
Mss 33272.

""This ten-page account by Blagden is in Cavendish's hand.
Cavendish Mss X(a). 8.

"Charles Blagden to Sir Joseph Banks, II May 1793, BI. Add
Mss 33272. 119-20. Henry Cavendish to Sir Joseph Banks, 23 Sep.
1793. copy. BM(MI). DTC, 8:257.

'"Sir Joseph Banks to Matthew Boulton. 6 and 10 July. 10 Aug.
1793, Birmingham Assay Office.

""'Henry Cavendish. "List of Stones W ith Their Examination,"
( lavendish Mss. Misc.

""This twenty-one page paper on strata in Cavendish's hand
docs not have a group number, but it is kept w ith the travel journals
in the Cavendish Mss.

'"-'Saussure. Voyages dims Its Mprs 2:i.

Copyrighleo

Earth

"truths" if not "a complete system of geology." 102
Deluc said that Saussure 's Voyages marked an epoch
in geology by showing that mountains are not
masses of rock but successively formed strata. As
Deluc now understood the task of geology, it was
to study mountains, hills, valleys, plains, and coasts
to learn the origin of the "mineral strata.""" The
geologist should draw on chemistry and mineralogy,
Deluc said, the point Saussure had made. At the
time of writing, 1 786, Saussure said that he had
studied the analysts Bergman, Scheele, Kirwan,
and others and that he too was now occupied with
the chemical analyses of minerals; he dedicated
himself not to the study of valuable metals in their
matrices but "principally to the study of rocks, a
study which by the confession of mineralogists and
to the detriment of their art, has been too much
neglected." 104 Kirwan, Cavendish's fellow chemist,
published a book on mineralogy in 1784 and later one
on geology; which explained "how to read the huge
and mysterious volume of inanimate nature, of which
mineralogy supplies the alphabet." 105 The interests
Cavendish had in common with Saussure, Deluc,
Kirwan, and others gave scientific meaning and
coherence to his activities on his several journeys.

The only geological author Cavendish
referred to in his notes on his journeys was John
Whitehurst, who like Michell was at the same time
an observer and a theorist. He was also what one
might call a local geologist, who studied the strata
of Derbyshire, which was close to home for
Cavendish. Whitchurst's book in 1778 laid out a
section of the strata underlying the great
Cavendish house in Derbyshire, Chatsworth. Henry
Cavendish subscribed to this book as did some
other Cavendishes and their relatives. Despite the
limited range of his observations, W hitchurst's goal
was a "system" of geology, of which Derbyshire strata
were just an illustration. There was, Whitehurst
believed, a constant order beneath the apparent
chaos of strata, and it could be inferred from the
impressions of vegetable and animals and from the
minerals. His natural history of the earth began
with Newton's law of gravitation, which showed
that the earth had a certain shape. Its composition
depended on attractions of other kinds, the
chemical affinities; Whitehurst cited Macquer. Its
mountainous surface had arisen from the expansive
force of steam; he cited Michell. Whitehurst listed
the order and thicknesses of the strata of Derbyshire,

325

the most puzzling constituent of which was toad-
stone, which Whitehurst concluded was volcanic in
origin, lava. 106 It was in connection with toadstone
that Cavendish mentioned Whitehurst, to disagree
with him. Cavendish, with Michell, believed that
toadstone was clay (as it happens Whitehurst was
right and Michell and Cavendish wrong)." 17
Cavendish made a close study of toadstone in
connection with this question of geological strata.

The journeys began at the same time that
Cavendish's chemistry changed direction. For
several years he had pursued a certain kind of
research, pneumatic chemistry, which, in effect,
came to an end with his paper on phlogisticated air
in 1785, the year he made his first journey with
Blagden. In 1786 he began keeping a new record of
chemical experiments, an indexed, bound book,
which he labeled "White Book No. l."><» It was a
transcription from his laboratory "minutes," some
of which (bearing telltale chemical stains) are
inserted loosely and not yet transcribed. The
experiments recorded in it, which go on to 1806,
might be called geological and industrial chemistry,
but the simpler name mineralogical chemistry would
not be misleading, given the often undifferentiated
eighteenth-century usage of "mineralogy," encom-
passing both ores and stones." 1 '' In light of
Cavendish's previous work in chemistry, this next
stage seems almost inevitable.

The four elements of the Greeks were still

iwjean Andre Deluc, An Elementary Treatise on Geology: Determining
Fundamental Points in That Science, ... and Particularly of the Huttonian
Theory of the Earth, trans 1 1, dc la Kite (London, mm, 41. 368.

IIM Saussiirc, Voyages dans les Alpes 2:ii, 120.

""Richard Kirwan. Geological Essays (London, 1 799), iii.

""John Whitehurst. An Inquiry into the Original State and Formation
of the Earth; Deduced from Farts and the Laws of Salute. To Which Is Added
an Appendix, Containing Some General Observations on the Strata in
Derbyshire . . . (London, 1778), ii. 2. 19-22. 94, 162, and plate 6.

'"'Cav endish's 21 -page summary of his observations on strata, p. 14.

l08 This book has 138 numbered pages, and 90 loose sheets are-
laid betw een the bound ones. Large blank spaces are left in the book
for cross-referencing and later additions. It is a copy book for
preserving results of experiments in narrative form. "White Book,"
Cavendish Mss. On p. 59 Cavendish referred to "2d book." w hich
suggests that there once was a "White Book No. 2." We note that
( )avendish was still using chemicals belonging to ( Charles ( '. i\ endish:
on pp. 61-62 of "White Book No. 1." Cavendish took a measure of
tineal (an Asiatic crude borax) "of my fathers."

"\ V Kyles, '" Tlie Kxtcni of Geological Knowledge mi the
Eighteenth Century, and Methods by Which It Was Diffused," in
Toward a History of Geology, ed. C. J. Sehncer (Cambridge. Mass.:
M.I.T. Press, 1969), 175.

""Robert Siegfried and Betty Jo Dobbs, "Composition, a
Neglected Aspect of the Chemical Revolution," Annals of Science 24
(1968): 275-93. on 276.

326

Cavendish

credible when Cavendish took up chemistry. 11 "
Macquer w rote in his Dictionary of Chemistry that
the "most probable opinion is, that as only one
kind of fire, of air, and of water, so only one kind of
simple elementary earth, exists." 11 ' In his way
Cavendish had acquired an understanding of three
of these elements, only one of which, water, was
perhaps elementary. Fire was not a substance for
Cavendish; the contemporary embodiment of it,
the elementary matter of heat, he rejected for the
motion theory of heat. Air was not an element
either, as Cavendish's work on the discrimination
of different gases helped to demonstrate. There
remained earth, a term which bore on the objects
of enquiry of his geological and industrial journeys
from 1 7SS. Earth was not an element either. Black,
in his chemical lectures, taught that there were at
least six earths, 11 - and Cavendish distinguished at
least that many. ,u Earths belonged to the mineral
kingdom and were the least studied of the classes
of minerals. Stones began to be studied as
composites of minerals, mainly earths, and the
preferred mode of study came to be chemical. The
Swedish chemist Axel Cronstedt proved that there
was no chemical difference between earths and
stones. 111 In an influential book on mineralogy in
175K, translated into English in 1770, Cronstedt
said that to make a "complete system" of mineral-
ogy, it was necessary to add chemical experiments
to the physical examination of mineral specimens,
and the "compleat tribunal" for settling miner-
alogical disputes was the "institution of a
laboratory." 115 In 1771, in the English version of
Macquer's Dictionary, the translator, James Keir,
added the chemical properties of a number of
minerals, w hich he learned from Cronstedt and the
work of several other chemists including his own.
The "most intelligent mineralogists agree," Keir
wrote, that the classification of minerals ought to
be based on an examination "chiefly of the
chemical properties, and not of external forms." 1 " 1
To Cronstcdt's compatriot Torbern Bergman, the
need for chemistry in mineralogy was obvious from
the unreliability of the external properties of
minerals (this before crystallography), their color,
size, hardness, texture, and form. These externals
were not exactly despicable, Bergman said, or even
dispensable, but their use was largely limited to
field identification. Bergman followed in Cronstcdt's
path, but he was even more rigorously the chemist:

Cronstedt, like other writers, put "volcanoes" in
their books, but Bergman did not: all that mattered
in mineralogy was what the minerals were made of,
not their history. That was consistent with
Bergman's understanding that the main purpose of
mineralogy was to make minerals useful to man. 117
Bergman was the first to give a standard procedure
for the chemical analysis of minerals. lls Cavendish
turned to this new domain of chemistry and
informed himself thoroughly, buying many books
on mineralogy. Though Cavendish published no
work of his own on minerals and strata, he left
ample record that he made this a serious study in
the last quarter of his life.

Contemporary mineralogists such as Bergman
put forward nomenclatures for mineralogy, but this
aspect of the science did not interest Cavendish.
This is the case even though classification in
mineralogy had a quantitative direction, which
might have interested him. 119 His indifference is
perhaps expected given his antipathy to what he
called the "present rage of name-making," w hich
was not limited to chemistry and botany.
Cavendish forbore using neologisms (except for his
occasional own), and in mineralogy with perhaps
better reason, since the mineral earth was an even
greater terra incognita than the reagents and
reactants on the chemists' shelves.

On his journeys Cavendish picked up
stones from the roadside and from gravel pits and
lime kilns and the like. Sometimes he did a quick
chemical test on the spot and a thorough one when

'"Article "Earths" in vol. 1 of Pierre Joseph Macquer, A
Dictionary oj Chemistry .... trans. J. Kicr (London, 1771 ).

"'Siegfried and Dobbs, "Composition." 27K-7''.

"'In the "White Book." Cavendish worked with a number of
distinct earths, verifiable earth, calcareous earth, siliceous earth,
argillaceous earth, earth of alum, and others.

"■•Rachel Laudan, From Mineralogy to Geology: The Foundations of
u Science, 1650-1830 (Chicago: University of Chicago Press, 19H7).
56-57, 63, 68.

"'Axel Iredric Cronstedt, An Essay Towards a System of
Mineralogy, trans, (i. von Engestrom, rev. E. M. Da Costa (London,
1770), vii, x. I lis mineralogy distinguished between simple minerals
and stones containing a variety of minerals, the latter of which he
excluded from his system.

"' Translator's preface to Macipier, Dictionary "I Chemistry, iv.

"'Torbern Bergman, Outlines of Mineralogy, trans. W. Withering
(Birmingham, 1783), 6-11. 127-2K.

'"" Thomas Thomson. History of Chemistry, Z vols. (London,
1830-31) 2:190-91.

"''Anders l.undgrcn, " The Changing Role of Numbers in IKth-
Century Chemistry" in The Quantifying Spirit in the 18th Century, eds.
T. Frangsmyr, J. L. Heilbron, and R. K. Rider (Berkeley: University
of California Press, I WO), 243-66, on 255.

he got home. He also brought home samples of
ores and products from the mines and furnaces,
which he subjected to the same kind of analysis.
Industry and nature produced complex substances,
which were equally grist for Cavendish's chemical
mill. The tremendous heat of industrial processes
was like the earth's interior and like Cavendish's
forges and furnaces at home, and their vats of
chemicals were like his bottles of chemicals from
the pharmacist. Mines and manufacturers were
great suppliers of substances of interest. They had
potential geological significance as well as meaning
for industrial operations.

British mining included tin and copper in
Cornwall and lead in Derbyshire (the dukes of
Devonshire owned lead mines there) but the main
direction was in stratiform deposits like coal; in
either case, there were technical processes, often
deep secrets of the trade, and in most cases they
were incompletely understood on the grounds of
science. The same can be said of manufacturing
processes. Unlike Continentals, the British did not
have mining academies and government jobs
waiting for their graduates. Owners, managers, and
engineers learned mining and metallurgy on the
job; their extensive knowledge was rooted in
practical experience and tradition. 120 There was
less incentive for systematic teaching and
development of mineralogy and geology in Britain
than abroad; at the same time, there was added
incentive for scientifically curious persons of means
like Cavendish to cultivate these sciences by field
and laboratory investigations. In pursuing a general
chemistry of minerals, encompassing rocks, earths,
kish, slag, slams, and refinery cinders, Cavendish
furthered his understanding of strata and provided
practical men with results of his chemical analyses.
Just as in his earlier studies of air, heat, and
electricity, in this late stage of his scientific work,
Cavendish was widely connected with other
persons; these connections he established by
leaving London on journeys, and it was to be
expected that they would be located in the
industrial provinces. As always, Cavendish's work
even when it was not published was not private but
a possession of science.

In his new work, Cavendish typically
proceeded by first giving a physical description of a
specimen and where it came from, then heating it
or grinding it or doing whatever else was needed to

help it dissolve in acid, and then often adding an
alkali to form a precipitate and then examining the
solution and the residue. The connection of
Cavendish's experiments on minerals with his
earlier work in chemistry is obvious through the
collection and weighings of gases; he could not
have done this work on minerals without his skills
in pneumatic chemistry as well as in analytic
chemistry. It would seem that several of Caven-
dish's later experiments related to Lavoisier's
chemistry, but in only one place did he refer to it.
In connection with coal and iron ore, in a paper he
gave to the engineer James Cockshutt, he said that
cast iron gives up less inflammable air than
hammered iron when dissolved in acid, "from
which Bergman & the partizans of phlogiston
conclude that ... it contains less phlogiston than
the latter & for the same reason the favourers of
the new system say that /it/ contains some
dephlogisticated air . . Here as in his paper
on the condensation of water Cavendish withheld
judgment on the competing theories, identifying
himself neither with the partisans of phlogiston nor
with Lavoisier's favorers. He did a number of
experiments on iron that Lavoisier would have
considered a confirmation of his theory but which
had phlogistic explanations too; Cavendish did not
comment. 122 Independently of the question of
phlogiston, the makeup of rocks and earths posed

,20 Laudan, From Mineralogy to Geology, 55-56.

'-' The paper used here has a watermark that does not appear on
paper Cavendish used before I7K.S. Given the subject of the chemical
analysis, the time would undoubtedly be 17H5 or later, when
Cavendish made his industrial and geological journeys. James
Cockshutt was a civil engineer instructed and sometimes employed by
John Smeaton. of Wortlcy Iron Works near Sheffield, w hom Cavendish
recommended for fellowship in the Royal Society on 26 Apr. 1K(>4.
Royal Society Certificates. 6. "Paper Given to Cockshutt" is a loose
insert between pp. 1 1 7 and 1 IK of Cavendish's "White Book."

'-'-Cavendish recognized that iron absorbed dephlogisticated air,
turning it into calx or finery cinder. "To Judge of the Dcphlog. of
Iron," ibid. He did an experiment, "Iron contained in calx of iron,"
concluding that the calx was 1.72 times the weight of the iron.
"W hite Book," p. 63. "On the Absorption of Deph. Air by Crass in
Dry ing," on pp. 121-24 of the "White Book," might be related to the
reason Cavendish gave for preferring the phlogiston theory over
Lavoiser's in his 1784 paper, namely, the constitution of plants.
Cavendish followed the work reported in the new French journal
created in I7K9 to disseminate the new antiphlogistic chemistry.
Annates de chemie. He cited it in connection with an experiment on
diamonds; from a report in the journal he calculated how much
dephlogisticated air diamond consumes in burning and how much
fixed air it gives off; and he concluded with his ow n experiments on
this point. "Comput. of Result of Burning of Diamond." Cavendish
\Ks. Misc.

328

great difficulties for chemists; the new anti-
phlogistic chemistry did not eliminate them and, in
some respects, complicated them further. 12 '

Whitehurst's proposal that there was a
worldwide deposition of strata 124 (which Michel!
believed too, apparently) would seem to have been
Cavendish's hypothesis. Despite Cavendish's
wide-ranging geological observations, he knew that
he had arrived at nothing worth publishing. In one
place he acknowledged that he was only scratching
the surface and that only superficial knowledge
could come of it. 125 He would surely have said the
same of his knowledge of industrial machinery. His
knowledge of the constitution of minerals was
extensive but largely happenstance, and again he
published nothing of it and showed no inclination
even to organize his experiments. The scientific
observations Cavendish made during and following
his journeys are easily associated with important
directions in the science of that time, as we have
seen, but there is a sense in which his journeys
were summer vacations too, justified by his active
curiosity about the natural and the manmadc land-
scapes outside London. A great reader of travels br-
others, as we know from his library holdings, he
was prepared to be enticed out of his study by
Blagden. His journals do not differ from travel
journals commonly kept at the time except perhaps
in their spareness. They have much in common
with the geological journals of the chemist W illiam
Lew is, Saussure, and Deluc and with the journal of
observations on strata and steam engines by
Cavendish's colleague Charles Hatchett. 1 -'' It is
hard to think of Cavendish enjoying himself, but it
seems that he did on these journeys, in his active
way. As his traveling companion, Blagden, observed,
Cavendish held up well on the journeys and
looked better for them.

Bristol Harbor

blagden and Cavendish together, probably
through Blagden, who had local knowledge and
connections, became involved in the problems of
Bristol Harbor in the 1790s. The problems by that
time had a long history. This busy harbor was
plagued by huge tides, which left ships stranded in
the mud, as Alexander Pope described: the scene
was a "long street, full of ships in the middle and
houses on both sides, /looking/ like a dream." 1 -' 7
The engineer John Smeaton had been brought in

Cavendish

in the early 1760s; Blagden's papers contain a
sketch by Smeaton of the rivers Avon and Frome, a
dam, a canal, and sluices. Plans for making one or
both rivers into a floating harbor were considered.
Time passed, the problems remained, and in 1791
the city's Society of Merchant Venturers resolved
that to make its port competitive with other ports, a
dam needed to be built across the Avon, with locks
on the river below its confluence with the
Frome. 12 * The greater part of the house sewers of
Bristol discharged into these waters, which posed
the problem that was presented to Cavendish:
would the proposed dam cause Bristol to suffer
smells from the sewage? Smeaton still and several
men of science were brought in as high-level
consultants, Adair Crawford, Bryan Higgins, and
Cavendish and Blagden. Benjamin Yaughan, who
had scientific connections with Cavendish, 12 '' sent
Cavendish papers about the project and asked for
his opinion. 13 " Cavendish declined to answer the
questions put to him on the grounds that only
physicians could answer some of them and that the
others were better answered by the engineers. The
data were too incomplete anyway for him to make
any determination. 131 Vaughan did not take no for
an answer. 13 - 7 Cavendish made some calculations
about the flows, 1,3 but it does not seem that he
helped Bristol with its sewage. There was no

'"Siegfried anil Dobbs, "Composition," 275-76.

'- J John Challinor, "Whitehurst, John," DSB 14:31 1-12.

1 "Archibald Geikie, "Note on Cavendish as a Geologist,"
( la\ endish, Sci I'ap. 2:432.

'-'''Saussure's Voyages. Deluc, (leologiail Travels. Charles Hatchett.
The Hatchett Diary. A Tour Through the Counties of England and Scotland
in 1706 Visiting Their Mines and Manufactures, ed. A. Raistrick (Truro:
I). Bradford Barton. 1967), F. W. Gibbs, "A Notebook of William
Lew is and Alexander Chisholm," Annals of Science K (1952): 202-20,
on 21 1.

l27 Pope quoted in Margaret C. Jacob. '//;/■ Cultural Meaning of the
Scientific Revolution { Philadelphia: Temple University Press. 19HH). 226.

'-'"Patrick McGrath, The Merchant Adventurers of Bristol (Bristol:
The Society of Merchant Adventurers, 1475). 159.

'-"'Benjamin Vaughan to Thomas Jefferson. 2 Aug. 17SH, in The
Papers of Thomas Jefferson, ed. J. P. Boyd, vol. 13 (Princeton: Princeton
University Press. 1956). 459-61, on 460.

'"'Benjamin Vaughan to Richard Bright. 21 and 29 Oct. 1791,
Bristol Record Office. 1 1 16K(3)r and 1 1 168(5)s. Benjamin Vaughan to
Henry Cavendish, 25 and 29 Oct. 1791. Cavendish Mss, New
( Correspondence.

Henry (Cavendish to Benjamin Vaughan, n.d., draft.
Cavendish Mss. New Correspondence. The mailed letter is dated 1
Nov. /1 791/. Bristol Record Office, 1 1 168(3)t.

li2 Benjamin Vaughan to Richard Bright. 2 and 50 Nov. 1791.
Bristol Record Office. 11168(6)r and 1116S(5)k. Richard Bright to
Benjamin Vaughan, 7 Dec. 1791. Blagden Letters. Royal Society. B..V25.

"'Henry Cavendish. "Data Extracted from Queries about
Bristol Intended Harbour." Cavendish Mss, Misc.

Earth

329

urgency, as more than ten years would pass before
there was any construction. With Bristol Harbor
Cavendish had a brush with practical science of a
civic kind that would become commoner in the
next century.

Hanks, Blagden, and Cavendish

Joseph Banks was a unique force in English
science in the second half of the eighteenth century;
though it was not for any significant research he
did, for he did none. He was an administrator who
directed a substantial part of the scientific energies of
a nation without an official scientific establishment.
On familiar terms with government ministers and
other useful persons, he moved in society as president
of the Royal Society and, through sheer force of
personality, as the embodiment of science. He was
a social creature of inexhaustible determination,
who began his day with a formidable breakfast by
invitation at his house, and before the day was
finished he had spoken w ith dozens of persons on as
many subjects and corresponded with as many more.
No one activity can sum up Banks's way of working,
but he may have shown himself to best advantage as
host of a regular Sunday salon in his house.

Cavendish was a faithful attender of these
Sundays at Banks's house. Since they were not
formal meetings. Cavendish could not know
everyone who would be there, and that was
unnerving. He was seen to hesitate on the landing
of Banks's house, evidently undecided if he could
bear the eyes of strangers on him, and would go in
only when someone came up behind him. 134 But
he did go in: Banks attracted the kinds of people
Cavendish liked, men of science and men of
action, world voyagers, and foreign travelers who
happened to be in London. One of the attenders of
Banks's Sunday gatherings compared and
contrasted them with gatherings at the homes of
aristocrats who had an interest in science. 1 " In the
associations he formed, Banks liked to think that
he did not favor the aristocracy, but he had a proper
appreciation of its importance. From Banks's
perspective. Cavendish, aristocrat and scientist at
once, was a welcome guest at the sober (tea-
drinking only) social gatherings of scientists and
patrons in a civilized setting (Banks's library),
which Banks called his "conversaziones," an
elegant word for an English at-home.

Banks and Cavendish, more than any of

their contemporaries, put their hearts and souls
into the Royal Society. They had that in common,
which enabled them to maintain a working rela-
tionship for the thirty-two years Cavendish served
the Society under Banks's presidency. 'Theirs was
at the same time a wary relationship, which could
never become a friendship. Too much was at stake
for both men, for Banks his authority within the
Society, for Cavendish the correct working of the
Society in his understanding of it.

The relationship between Cavendish and
Blagden began in 1782 and changed in some way
in 1789. Someone said it did not "suit." 136
However, the break, as we have pointed out, w as in
the first instance between Blagden and Banks,
with Cavendish the affected third party. Blagden's
services to the Royal Society and to Banks could
not easily be distinguished. Banks so identified
himself with the Society that a good measure of
personal loyalty was an inevitable part of the job of
a secretary of the Society. Blagden recognized and
accepted that, but after a few years, he wanted out
of what he perceived as a one-way relationship. In
early 1788 he wrote to Banks that he intended to
resign as secretary, and on the same day he sent a
copy of that letter to Cavendish, explaining that he
was taking this step to prevent him and Banks from
becoming a 'violent mixture." 1 " Three days later
Blagden wrote to Watson, who evidently had
intervened to make peace, that he would sacrifice
himself no longer. 1 ™ He told Banks that his
secretaryship of the Royal Society was the "great
misfortune" of his life, and that this had to do with
his "connexion" with Banks. IW Banks replied that
he had no idea what Blagden was talking about,
whether Blagden's complaints were leveled at him

,M Ceorge Wilson. The Life of the Honourable Henry Cavendish
(London. 1851), 169.

'"Sometime after 1805, the young anatomist and surgeon
Benjamin Brodie was invited by Banks to his Sunday meetings,
where he saw Cavendish together with scientists, distinguished
foreigners, and noblemen whom Banks regarded as patrons. By their
intimacy and regularity, Banks's .Sunday meetings were distinguished
bv Brodie from those held three or four times a season by the duke
nl Sussex, the marquis of Northampton, and Lord Rossc. Timothy
Holmes. Sir Benjamin Collins Brodie (London, 1898). -46. 68.

'MVilson, Cavendish, 129.

'"Letters from Charles Blagden to Sir Joseph Banks. 1 Feb.
1788, draft, and to Henry Cavendish, 2 Feb. 1788. Blagden Letters.
Royal Society, B.38-39.

""Charles Blagden to William Watson. 5 Feb. 1788. draft.
Blagden Letterbook. Roval Society, 7:1 15.

' ''Charles Blagden to Sir Joseph Banks, 27 Mar. 1789, BL, Add
Mss 33272. pp. 56-57.

330

or at the world in general. He had thought they
were friends but now he feared they were enemies. 14 "
Hanks said he was taken by complete surprise.

Blagden's misery was exacerbated by
Banks's assignment to him of a problem that he
had accepted in the name of the Royal Society: to
find a way to determine the correct excise duty on
alcoholic beverages. The Swiss chemist Johann
Caspar Dollfuss, then in London, had started work
on the problem by establishing a "standard" for the
specific gravity of pure alcohol at sixty degrees of
heat. Dollfuss left London, and his experiments
w ere repeated by George Gilpin, clerk of the Royal
Society, who then recommended other
experiments for Blagden to make. Cavendish gave
Blagden assistance by developing a rule for
figuring duty; the distillers objected to it, but
Blagden adopted it for the reason Cavendish gave,
of preventing fraud. 141 The determination of the
specific gravity of a mixture of pure alcohol and
water was not straightforward, owing to the mutual
penetration of alcohol and water and to the
different expandabilities of the two liquids with
heat. The experiments on varying proportions of
alcohol and water were done by weighing, the most
accurate way. Blagden recommended that the
government set duty strictly by specific gravity, not
by the old "proof." He prepared tables calculated
to th e places but due to the error of the experi-
ments, only three places could be counted on, the
number of places Blagden accordingly proposed for
practical tables at excise. He published a paper on
these experiments in this "so material a branch of
the revenue" in the Philosophical Transactions in
1790. 14 - It undoubtedly had cost him a lot of time.

Blagden thought he should have been paid
for this tedious business of the excise duties, which
was Banks's business in any case; the literary
reward, a publication, did not begin to compensate.
Banks replied that he had done many jobs for the
government and never thought of reward, but he
would look into the possibility of payment if
Blagden would tell him what he expected.
Blagden's resentment of Banks had been building,
and now it all came out. From the time he returned
from America, Blagden believed, Banks had taken
him for granted, and deceiv ed him, and made him
a "tool of his ambition." When Blagden took the
job of secretary to the Royal Society, he believed
that Banks would advance him in society and

Cavendish

improve his fortune. Banks did nothing of the kind
but instead, Blagden believed, discouraged him
from pursuing his profession, medicine, and even
from marrying, Banks's purpose being to keep
Blagden dependent on him. Banks defended his
character and conduct. 145 Blagden's rancor at Banks
continued and so did their correspondence until it
became tedious. 144

It has been said that Cavendish made
Blagden his associate on the condition that he give
up medicine and devote himself to science. I4S The
contrary would seem to be the truth. Blagden
reminded Banks that in 17X4, some two years after
Blagden had become Cav endish's associate, he had
told him that "Mr Cavendish wished me to
prosecute seriously the profession of physic," but
that Banks had discouraged him. 14 ' 1 Blagden
seemed to have abandoned the idea of returning to
medicine at about this time, writing plaintively to
people about "being now quite out of the practice

l4 "-Sir Joseph Hanks to Charles Blagden. n.ci. /after 2K Mar.
1789/, BL Add Mss 33272, p. 58.

141 "Remarks by Mr. Cavendish," Bladder) Collection, Misc
Notes. Royal Society, No. 65. Charles Blagden to llenrv Cavendish.
12 and 26 Mar. 179()', draft, Blagden Lctterbook. Royal Society, 7:317
and 7:695. Once again Cavendish made available experimental
results of his father, this time a table of the expansion of water with
heat. "From the Kxperimcnts of Lord Charles Cavendish.
Communicated by Mr Henry Cavendish. March 1790," Blagden
Collection. Misc. Notes. Royal Society. No. 99.

'■"-'Charles Blagden, "Report on the Best Method of
Proportioning the Excise on Spirituous Liquors,"/''/' SO (1790):
321— 15. quotation on 345. Jesse Ramsden published a pamphlet
criticizing the report. .1// Account of Experiments to Determine the Specific
Gravity of Fluids (London, 1792). Blagden did the experiments all
over again to eliminate a source of error, publishing the results in a
second paper, "Supplementary Report on the Best Method of
Proportioning the Kxcise upon Spirituous Liquors," /'/' 82 (1792):
425-38. George Gilpin published an immense series of tables, in
small print, based on the experiments reported by Blagden: "Tables
for Reducing the Quantities by Weight, in Any Mixture of Pure-
Spirit and Water, to Those by Measure; and for Determining the
Proportion, by Measure, of Kach of the Two Substances in Such
Mixtures." /'7'84 ( 1 794): 275-382.

""Charles Blagden to Sir Joseph Banks, 28 Mar. 1789, BL. Add
Mss 33272, pp. 56-57. Sir Joseph Banks to Charles Blagden. 15 July
1789. Blagden Letters, Royal Society, B.39. Charles Blagden to Sir
Joseph Banks. 25 July 1789, Blagden Collection. Royal Society, Misc.
Matter — Unclassified. Sir Joseph Banks to Charles Blagden, 31 July

1789, Blagden Letters, Royal Society. B.40.

'"Charles Blagden to Sir Joseph Banks, 27 Mar. 1790, BL, Add
Mss 33272. p. 73. Sir Joseph Banks to Charles Blagden, n.d., draft,
ibid., 73-74. Charles Blagden to Sir Joseph Banks, 2<S and 29 Mar.

1790, 3 Apr. 1790, ibid., 75, 79. Sir Joseph Banks to Charles Blagden.
n.d.. draft, ibid., SO. Charles Blagden to Sir Joseph Banks, 8 Apr.
1790. ibid.. SI.

IJS Hcnry. Lord Brougham, "Cavendish," in Lives of Men of Letters
and Science Who Flourished in the Time of (icoi^e III, vol. I
(Philadelphia. 1X45). 250-59. on 258.

"' Blagden to Banks. 8 Apr. 1790.

0upyiqhM>

Earth

331

of physic" and therefore unable to advise on
remedies,' 47 and being as little familiar with
inoculation and other topics of medicine "as if I
had never been of the profession." 148 Blagden now
blamed Banks for encouraging him to abandon his
profession and then not compensating him.

There is a draft of a letter in Blagden's
papers that may have been addressed to Cavendish
but we suspect that it was addressed to their
common friend, the always helpful physician
William Heberden. It reads: to make Banks's
"ungenerous, (if not treacherous) conduct the more
evident, let me contrast it with your own. You, to
whom I had not had any opportunity of being
serviceable, seeing how unwisely I neglected my
profession had the goodness not only to advise me
to resume it, but likewise to offer that you would
bear all the pecuniary risk attending the pursuit, so
that my private fortune should at all events remain
unimpaired. I am sensible how imprudently I acted
in not following your advice; but at that time I had
still the weakness to believe Sir J.B.'s professions
sincere." 149 Blagden wrote of the "generosity of
your conduct in your original offer, in your subse-
quent present of this house, in your late
confirmation of that present, and especially in your
further offer when I expected to marry last year."
Blagden expected to marry in 1789. The house he
lived in, from 1784, was on Gower Street, just a few
doors from Cavendish's house on Bedford
Square. 150 The reason we think that the benefactor
in question is Heberden is the timing and message
of a letter from Blagden to Banks in late 1783. In
this letter, Blagden spoke of "Heberden's
proposal," and he felt out Banks, asking his advice
on how to decline the proposal. The proposal had
to do with Blagden's practice of medicine; if he did
decline, Blagden said, he probably would never
have another chance to practice. 151 There is
another letter, however, that may have been
addressed to Cavendish, in which Blagden spoke
of the "liberal offer" the recipient had just made on
a house. 152

This much is clear: in 1789 Blagden was on
good terms with Cavendish and bad terms with
Banks. That summer, to free himself from his
servitude to Banks, as he saw it, Blagden
contemplated going abroad with friends, Henry-
Temple, second viscount Palmerston and his wife,
Lady Mary, and staying away all the coming winter.

His concern with that plan was Cavendish, who
raised one objection: it would interfere with what
Blagden had "more at heart than any object in
life," his return to medicine (and possibly marriage
too). Blagden thought his chances of practicing
medicine at the resorts abroad were as good as in
London. But if by being away he would hold up
Cavendish in any of his pursuits, he would stay
home. 153 Cavendish gave his blessing, and Blagden
left with the Palmerstons. Before he did, he sold
his house and its furnishings on Gower Street, with
the thought that he would never again have a
permanent address in England. Persons with mes-
sages for him were to be directed to Cavendish's
house on Bedford Square. His bureau containing
private papers was left in Cavendish's bedroom,
and Cavendish was given the key and instructed to
open the bureau and keep or burn the papers if
Blagden should suffer an accident. 154 Blagden had
recently turned forty and his life seemed headed
nowhere, as he set out on yet another Continental

14 'Charlcs Blagden to William Farr. 14 Nov. 1785. draft. Blagden
Letterbook. Vale.

'■"•Charles Blagden to Francoisc Dclarochc, 1 Dee. I78o, draft,
Blagden Letterbook. Yale.

'♦'Draft of letter in Blagden Collection. Misc. Notes, Royal
Society. No. 224. This letter is after 28 Mar. 1789, and because of the
similarity of content and wording to a letter from Blagden to Banks
on 8 Apr. 1790, it is probably around the latter date.

""Charles Blagden to his brother. John Blagden Hale, /Oct. or
Nov. 1784/, draft. Blagden Letterbook, Yale.

"'Charles Blagden to Sir Joseph Banks, 16 Oct. 178.V BM(NH),
DTC 3:127-31.

142 The letter reads: "Just after you were gone Mr. Ilanscombc
called here with the inclosed note, & opened it; he had
/undeciphercd/ before at your house, but having been informed you
were gone by to I lampstead came to shew it to me. I am extremely
obliged to you for the liberal offer you have made; but as, were I so
rich that the sum would be no object to me I should still think it too
much for the house. & »ho d probably refuse to give it. I cannot but
consider it as totally inequitable that you sho J give it for me. I
therefore do most seriously request that you would refuse to comply
with the terms proposed, & wait till an opportunity offers of making
a fairer purchase; and in the mean time I will use every means in my
power to become reconciled to my present situation." Charles
Blagden to /Henry Cavendish?/, n.d., draft. Blagden Collection.
Royal Society, Misc. Matter — Unclassified. In 17H4 Cavendish still
had his country house at I lampstead, the place referred to in the
letter above.

'"Charles Blagden to Henry Cavendish. Aug. 1789. draft,
Blagden Letters, Royal Society, 7:694.

'^Charles Blagden to John Blagden Hale. 17 Sep. 1784; "An
Inventory of Furniture etc. Taken September VI 789 at Dr.
Blagden's House in Gower Street Appraised & Sold to Hill Esqr.,"
Gloucestershire Record Office, D 1086. F 155 and F 157. Charles
Blagden to Mr. Lewis, 15 Sep. 1789, Blagden Letterbook. Royal
Society. 7:306. Blagden to his brother. 16 Sep. 1789, ibid., 7:309.
Blagden to Henry Cavendish, 16 Sep. 1789, Blagden Letters. Royal
Society, B. 166b.

332

journey, evidently with gloomy premonitions.

When Blagden's marriage was in prospect.
Cavendish entered into his plans in an essential
way. In 1789 the potential wife was picked out, and
in November of that year Blagden asked his
brother to inform him about her. Would she enjov
Blagden's kind of company and "particularly would
so far enter into the pursuits of my friend Mr. C. as
not to think some portion of time spent in his
company tedious? This would be a matter of the
utmost consequence to us both. You will easily
suppose I do not mean that she should enter into
our studies, but simply that she should not find it
disagreeable to be present when such matters were
the subject of conversation, or when any
experiment which had nothing offensive in it, was
going on."'- ss Blagden contemplated the three of
them together. Cavendish, he, and his wife. He
was not worried about Cavendish's reaction but
hers. Blagden knew Cavendish very well, and his
plans to continue his work with Cavendish in the
presence of his wife bring into serious doubt the
anecdotal absolute misogyny of Cavendish. In one
of his letters of reproach, Blagden told Banks that
he "had great reason to believe Mr. Cavendish
would assist me in making such a settlement as the
family could not properly object to." 156 From the
letters of 178° and 1 790 we see that Cavendish was
a friend to Blagden in need. Blagden did not
resume his profession, and the marriage did not
happen either. Lord Palmerston did not go on to
Italy to spend the winter, as planned, and in the
late fall Blagden returned to resume his job as
secretary of the Royal Society. In time Blagden's
relations with Banks settled down. Out of all that
emotional turmoil, nothing much changed, which
might be how Blagden wanted it to come out. On
the day Cavendish died, Blagden told Banks that
Cavendish always knew "what was right for him,"
that Cavendish was a "true anchor." 157 Blagden
admired in Cavendish w hat he himself lacked.

As Blagden saw it, Cavendish encouraged
him in the direction of independence, whereas
Banks used him. From Banks's point of view,
Blagden had got what he seemed to want, with
Banks's help; Banks deserved no blame at all, if
anything credit. If Blagden did not know or say
w hat he wanted, there was nothing Banks could do
about it. Blagden placed all blame for his
unhappiness on Banks, and Banks saw himself as

Cavendish

entirely blameless. Neither man showed any
insight into their relationship, though Blagden,
who experienced what we might call a breakdown,
might hardly be expected to.

Blagden made himself easily available, ever
offering himself to Banks, with Banks ever
accepting. After their quarrel, they resumed their
friendship, but it had an edge to it. Banks could be
wounding, as he was when Blagden considered
stepping down as secretary of the Royal Society.
He had been elected to that job for fourteen
successive years, and in his opinion he had burned
his eyes out for it. It had got so bad that he could
no longer read papers at the meetings (with the aid
of candle light). But he wanted to leave open the
possibility of resuming the job later, and Banks told
him, in effect, to forget it. Blagden's "enemies"
would bting up his absences on his travels, and
they would accuse him of "not cultivating science
with the same ardor as you have formerly done,
owing to the habits you have lately adopted of
mixing much in the gay circles of the more
elevated ranks of society." 158 Blagden replied with
indignation: he had "never performed the office so
well" as he had last winter. Blagden resigned for
good in the winter of 1797."'"

One thing did change at the time of
Blagden's charges against Banks, and probably
because of them. The relationship between
Blagden and Cavendish was less close afterwards.
Like their original understanding, their new one,
whatever it was, was evidently not written down.
We can safely assume that Cavendish did not want
to quarrel w ith Banks, and it might hav e seemed to
him prudent to keep an impartial distance from
both parties. We assume that the distancing was
desired by Blagden too.

As with Banks, with Cavendish Blagden

'"Charles Blagden to his brother, John Blagden Hale, 13 Nov.
17X9. draft. Blagden Papers, Royal Society, box 5, ("older 49.

ls, 'Charles Warden to Sir Joseph Hanks. H Apr. 1790. BL Add
Mss 33272, p. 81.

>'- 7 24 Feb. 1810. Blagden Diary. Roval Society. 5:426.

•"Joseph Banks to Charles Blagden. 27 Apr. 1797, Blagden
Letters, Royal Society. B.44.

"'Charles Blagden to Joseph Banks. 17 Apr. 1797. BL Add Mss
33272, pp. 158-59.

'"'He resigned on 30 Nov. 1797. The letter of resignation is in
his papers, undated and without address. It begins: "The
inflammation of my eyes . . ." Blagden Collection. Royal Society.
Misc. Matter — Unclassified.

Earth

333

continued to have a close association. Blagden
never doubted that in the case of his friend
Cavendish, he was in the presence of greatness.
Writing to Banks from Paris in 1802, Blagden
compared Cavendish and Laplace: "Laplace, who
is as much superior among them here as Mr
Cavendish is with us." 161 On Cavendish's death
eight years later, Blagden wrote to a correspondent

in Paris that Cavendish was "by much the best
philosopher in my opinion that we have, or have
had, in my time, at the R.S." 162

i" 1 Sir Charles Blagden to Sir Joseph Banks. 1 Apr. 1802, BL Add
Mss 33272, pp. 172-73.

"'-Sir Charles Bladen to B Delessert, 20 Mar. 1810, Blagden
Letters, Royal Society. D 44f;.

Copy lighted mai

CHAPTER 7

Weighing the World

Cavendish lived all of his adult life in and around
London in solid houses with servants to protect his
privacy. These houses he turned into places of
science, where the drama of his life was staged,
unseen, internal, and profound. 1

In 1810, an anonymous biographical notice
of Cavendish was published in the Gentleman's
Magazine. 1 The author was Blagden, we know, be-
cause his papers contain an otherwise unidentified
fragment of the notice in his handwriting. The
circumstances are explained in two letters to Blagden
from Lord George Cavendish, Henry Cavendish's
main heir and in entries in Blagden's diary.
Evidently, Lord Ceorge had written a sketch of
Cavendish's character to go in the papers when
Cavendish's remains were removed from Clapham,
and at dinner with Banks and Blagden, he asked
Blagden to "fill it up."' Blagden wrote his sketch
then and showed it to Banks and Lord George the
next day. 4 Lord George wished that Blagden had
altered the part about Cavendish's character, which
probably referred to what he himself had written,
and he said he would consult with the duke of
Devonshire about this family matter. 5 Lord George
next wrote to Blagden that the duke of Devonshire-
had approved his sketch of Cavendish's "character"
for the "Publick Papers." In a second letter, written
the next day, Lord George informed Blagden that
some corrections Blagden meanwhile had sent him
had arrived too late (they had not, as it turned out),
since being concerned that nothing about Caven-
dish should appear in print before Blagden's notice,
he had already sent the notice to press. At the
bottom of Lord George's letter, Blagden wrote out
again the three corrections he had requested, two
of which are of no consequence here. The third
correction says that Blagden wanted Cavendish's
habits to be called not "retired" but "secluded."''
"Retired" and "secluded" each conveyed much the
same impression, but there was a nuance. "Retired"
suggested withdrawn or inactive, "secluded" shut
up. 7 The second word, Blagden (and perhaps Lord

George) decided, was the better (and more force-
ful) word for Cavendish.

The best word for characterizing Cavendish's
biographers is bewilderment. Cavendish's scientific-
manuscripts confront them with studies on every
topic in the physical sciences, carried out
independently of one another, without rhyme or
reason other than with the implicit goal of totality
of understanding. That is a first impression. If the
biographers persist, they see that the studies fall
into groups, connected by large goals, which
belong to the goals of the science of Cavendish's
time. One extended group of papers has to do with
his researches on the earth, including its gaseous
envelope and its location and orientation in the
solar system. Researches on the earth that were
most significant for eighteenth-century science
tended to involve numbers of investigators working
together, in contrast to researches on general laws
of nature, which tended to be done by individuals
working on their own, at least in the first instance.
In the several organized researches on the earth
that Cavendish took part in, he worked with others
while preserving his measure of essential privacy.
In his last published experiment, the determi-
nation of the mean density of the earth, he worked
in seclusion in the ordinary sense of the word. I le
brought the earth into his place of seclusion, his
home, where he experimented on it virtually alone.

■The discussion in this chapter is taken from Russell
McCormmach, " The Last Kxperiment of Henry- Cavendish," in 'No
Truth Except in Details': Essays, in Honor of Martin .1. Klein, eds. A. J.
Kox and D. M. Siegel (Dordrecht: Kluwcr Academic Publishers,
1995), 1-30. We acknowledge permission to use material from this
chapter: Copyright Kluwcr Academic Publishers 1995: reprinted by
permission of Kluwcr Academic Publishers.

^Gentleman's Magazine. March 1810. 292.

'If we get the sense of the entry right: 6 Mar. INK). Blagden
diarv. 5:back p. 431.

*7 Mar. 1810. Blagden diary, 5:431.

^8 Mar. 1810, Blagden diary, 5:back p. 431 and p. 432.

'■Lord George Cavendish to Sir Charles Blagden, 9 and 10 Mr.
1810, Blagden Letters, Royal Society, C.17 and G.19.

'"Shut up apart" is an eighteenth-century meaning of "seclude."
Oxford Universal Dictionary, 3rd rev, cd.. 1935. p. 1825.

Cavendish

Then because it was science he was doing, he
communicated his results. The experiment of
weighing the world came to be known to scientists
as the Cavendish experiment. It was well named.

The Density of the Earth

Cavendish's interest in weighing the world
is on record in a letter he wrote to John Miehell in
1783. He knew that Miehell was already in trouble
with the telescope he was building because of its
tremendous scale. He w rote: "if your health does not
allow you to go on with that /the telescope/ 1 hope it
may at least permit the easier and less laborious
employment of weighing the world. " x This letter of
1783 contains the earliest mention of Michcll's
"weighing the world." "Kxperiments to Determine
the Density of the Karth," Cavendish's paper in the
Philosophical Transactions for 1798. opens with an
explanation of his and Michcll's connection.

Many years ago, the late Rev. John Miehell, of this
Society, contrived a method of determining the
density of the earth, by rendering sensible the
attraction of small quantities of matter; but, as he
was engaged in other pursuits, he did not
complete the apparatus till a short time before his
death, and did not live to make any experiments
with it. After his death the apparatus came to the
Rev. Francis John Hyde Wollaston, Jacksonian
Professor at Cambridge, who, not having
conveniences for making experiments with it, in
the manner he could w ish, was so good as to give
it to me.''

Miehell died in 1793. and he had not finished
building his apparatus until shortly before then.
Michcll's instruments and, probably, some
apparatus were left to his former college at
Cambridge, Queen's. 1 " Just how the apparatus
came into Wollaston 's hands Cavendish does not
say, nor does he say who initiated the gift of the
apparatus from Wollaston to Cavendish, though
from all that passed before, it was almost surely
Cavendish. In any event, Miehell, Cavendish, and
Wollaston were all on familiar terms. Wollaston
belonged to a dynasty of men of science and the
Church, all of whom, like all of the principals in
weighing the world — Cavendish, Maskelyne, and
Miehell — were Cambridge men. The educational,
scientific, and personal connections between the
Wollastons, Miehell, and Cav endish are hard to keep
in mind, giv en the large number of Wollastons and
the family parsimony in assigning first and middle

names." It is — this is the point — entirely reason-
able that Michcll's apparatus should end up in
Cambridge with one of the Wollastons, and that
Cavendish knew its whereabouts, coveted it, and
was given it to use.

Cavendish was nearly sixty-seven when he
weighed the world. His most recent publication of
experiments had been on chemistry ten years before,
and it would have been his last if it had not been
for Michcll's work, which Cavendish finished for
him. Cav endish's experiment was, in reality, several
"experiments," seventeen in number, each consisting
of many trials. The first experiment was done on 3
August 1797, and the first eight were done a few
days apart through the rest of August up to the last
week in September. The remaining nine experi-
ments were done the following year, from the end of
April to the end of May. The paper reporting the
experiments was read to the Royal Society on 21
June 1798, just three w eeks after the last experiment.
The long paper with its lengthy calculations must
have been largely written by the end.

"Cavendish added: "for my own part I do not know whether I
had not rather hear that yon had given the exper. /of weighing the
world/ a fair trial than that yon had finished the great telescope."
Henry Cavendish to John Miehell. 11 May l7K.i. draft. Cavendish
Mss. New Correspondence.

'Henry Cavendish, "Kxperiments to Determine the Density of
the Karth." PTSS (179H): 469-526; in Cavendish. Sri. Pap. 2: 249-86,
on 249.

'""Miehell. John." D.XH 13:333-34, on 334.

"Wollastons father. Francis, horn the same year as Cavendish,
took his degree in law lint entered the Church instead. He had a
passion for astronomy, and he had his own observatory with first-class
instruments. With at least that much in common, in 176K Cavendish
brought Francis Wollaston as a guest to a meeting of the Royal
Society on K Dec. 176K; Wollastons certificate is dated 12 Jan. 1769
and signed by Cavendish along with Maskelyne and several other
prominent members; Wollaston was elected that vear. Royal Society.
JB26: 1767-1 770; Royal Society, Certificates, '3:65; "Wollaston.
Francis," DSB 21:778-79. One of Francis Wollastons sons. William
Hyde Wollaston. was an eminent chemist. Cavendish proposed him,
as he had his father, as a member of the Royal Society, and he too was
elected: Royal Society, Certificates. S (<> May 1793); "Wollaston.
William Hyde." D.XH 21: 7K2-K7. on 7H>. Another of Francis's sons,
George Hyde Wollaston. was one of Cavendish's neighbors at
Clapham Common, where Cavendish performed his experiment on
the density of the earth. "Wollaston of Shenton," Burke's Genealogical
and Heraldit History of the Landed Gentry (London, 1939), 2479. George
Hyde Wollastons house as well as Cavendish's are on the map of
Clapham Common. "Perambulation of Clapham Common 1800,"
from C. Smith. Actual Survey of the Rout/ from London in Brighthe/mston.
"let another of Francis's sons was Francis John Hyde Wollaston.
Jacksonian Professor of Chemistry, from whom Cavendish received
Michcll's apparatus. Michcll's association with the Wollastons went
back as far as Cavendish's. To give but one indication: as a recently
elected Fellow of the Royal Society, Michcll's tlrst recommendation
for a new member, in 1762, was lor Francis's youngest brother.
George Wollaston. Fellow and Mathematical Lecturer of Sidney-
Sussex College, Cambridge. "Wollaston. Francis," 779.

Copyrighted maer

Weighing the World

Cavendish began the report of his work
proper with what in an experimental paper is a
promising beginning: "The apparatus is very simple."
The apparatus, whieh Cavendish largely remade, is
in truth easily described. Its moving part was a six-
foot wooden rod suspended horizontally by a
slender wire attached to its center, and suspended
from each end of the rod was a lead ball two inches
across. The whole was enclosed in a narrow wooden
case to protect it from wind. Toward the ends of
the case and on opposite sides of it were two
massive lead balls, or "weights," each weighing
about 350 pounds. The weights could be swung to
cither side of the case to approach the lead balls
inside, and in the course of the experiment this was
regularly done. The gravitational attraction between
the weights and the balls was able to draw the rod
sensibly aside. From the angle of twist of the rod,
the density of the earth could be deduced; but for
this to be done, the force needed to turn the rod
against the force of the twisted wire had to be
known, and for this it was necessary to set the rod
moving freely as a horizontal pendulum and to
observe the time of its vibrations.

To the modern reader the way Cavendish
got from the mutual attraction of the lead
"weights" and balls to the density of the earth
seems roundabout, which is to be expected.
Cavendish did not write equations, and he did not
distinguish between weight and mass, and so no
gravitational constant appears. He introduced an
artifice, a simple pendulum, the length of which
was one half the length of the beam of his
apparatus. The simple pendulum, which was not
part of the experiment but only of the analysis,
oscillates in a vertical plane under the action of the
earth's gravity. It does not look at all like Cavendish's
horizontal beam oscillating freely as a horizontal
pendulum, but the two pendulums are described
mathematically the same way; they are both
"pendulums" performing simple harmonic motion.
By combining and manipulating the formulas that
relate the forces on the two pendulums, certain
proportionalities result, which include the wanted
expression for the density of the earth in terms of
the measures of the apparatus and two things
observed in the experiment, the period of the
torsion balance and the displacement of the beam
when the weights were swung from one side to the
other. The reason why the earth enters this expres-

337

sion is that the "weights" have weight owing to the
attraction of the earth, which is proportional to the
matter of the earth. Using modern terminology and
notation, this derivation can be done with a few
lines of equations, but they would not correspond
to Cavendish's reasoning. 1 -

In the earlier experiment of the Royal Society on
the attraction of mountains, it was an open
question whether or not a mass the size of a
mountain was sufficient to cause a detectable
effect. In Cavendish's experiment, the detectable
effect was readily achieved by weights small
enough to fit into an apparatus. The lead balls were
what he "weighed" with his apparatus, thereby
weighing, indirectly, the world. This was not an
obvious weighing like the chemist's weighing with
his balance (Cavendish, the chemist, was
renowned for his weighings of this sort). 13 Rather it
measured the attraction of lead spheres, which led
by a chain of theoretical arguments to the weight,
or density, of the world.

Cavendish's experiment was a precision
measurement of a seemingly inaccessible magnitude.
Newton had made the calculation of the attraction
of two one-foot spheres of earth matter placed one-
quarter inch apart to show that the force was too
feeble to produce a sensible motion; he thought it
would take a month for the spheres to cross the
quarter inch separating them. 14 The force between
the spheres in Cavendish's experiment was only

'-'The modern analysis of Cavendish's experiment is simpler
than Cavendish's. But what modern accounts usually say Cavendish
did. he did not do. The universal gravitational constant he did not
derive, though it can be readily derived from the results of his
experiment. This is the point of B. E. Clotfeltcr, " The Cavendish
Experiment as Cavendish Knew It," American Journal of Physics 55
(19H7): 210-13. Cavendish's object was to determine the density of
the earth, and there is nothing in his analysis to require the
gravitational constant, nor is there any reason why. at that time, he
should have regarded it as desirable. Although it is not necessary to
derive the gravitational constant, the unit of force sunKcsts it. and the
unit of force did not yet exist for expressing !•' = GMiMilr , the
attraction between two masses. Mi and l/j. separated by distance r.

'■'The chemist's balance teas used to determine the earth's
density, but later, in attempts to improve upon Cavendish's
experiment; notably by I' J. (i. von Jolly in IK7H-80, J. II. Poynting
in 1890, and F. Richarz anil (). Krigar-Mcn/.cl in 1(WK. Kdward
Thorpe, "Introduction." Cavendish Set. Pap. 2:1-74, on 72-73.

IJ ln his System of the WorM. Newton asked why, since all bodies
attract, we do not see them do it on earth. His answer was that
"experiments in terrestrial bodies do not count," and the reason they
do not he show ed by a calculation: "a sphere of one foot in diameter,
and of a like nature to the earth, would attract a small body placed
near its surface w ith a force 200000(10 times less than the earth would

Cavendish

PLA1 E XIII. Apparatus for Weighing the World. In Cavendish's modification of John Michell's apparatus, the lar«e spheres R are the weights that
attraet the small spheres, which are suspended from the arm. which in turn is suspended by the tine wire gl, The room in which the apparatus is
housed is also show n and as well as the arrannenicnts for view ing it from outside the room. "Experiments to Determine the Density of the Earth."

Philosophical Transactions «« ( 1 7'M): Sl<>.

1/50,000,000 part of their weight, so that the minutest
disturbance could destroy the accuracy of it. To
guard against any disturbance, Cavendish placed
the apparatus in a small, closed "room," about ten
feet high and as many feet across. I ; rom outside
the room, he observed the deflection and vibration
of the rod by means of telescopes installed at each
end. Verniers at the ends of the rod enabled him to
read its position to w ithin l/100th of an inch. The
only light admitted into the room was provided by
a lamp near each telescope, which was focused by a
convex lens onto the vernier. The rod and weights
were manipulated from outside the room. In doing
the experiment. Cavendish brought the massive
weights close to the case, setting the rod in motion.
Then peering through the telescope into the semi-
dark room, he took readings from the illuminated
vernier at the turning points of the motion, and he-
timed the passing of the rod past two close-K ing,
predetermined divisions. The experiment was a
trial of the observer's patience: depending on the
stiffness of the suspension w ire, a single vibration
could take up to a half hour, and a single experi-
ment might take two and one half hours.

Much of the time Cavendish spent on the
experiment was devoted to errors and corrections.
He traced a minute irregular motion of the rod to a
difference of temperature between the case and
the weights, which gave rise to air currents. One
entirely negligible correction he published as an
appendix to his paper. This was the attraction on
the rod and balls of the mahogany case that
enclosed them, the counterpart of Cavendish's
previous calculation of the attraction of ideal
mountains: it amounted to an exhaustive summing
of the attractions of the box on the movable part of
the apparatus, only instead of the cones and other
figures he had used to represent mountains, here
he used rectangular planes to represent the regular
boards of the wooden case. It is fitting that

do if placed near its surface: but so small a force could produce no
sensible effect. If two such spheres were distant but by '/a. of an
inch, they would not, even in spaces void of resistance, come
together by the force of their mutual attraction in less than a month's
time." Isaac Newton. Sir Isaac Newton's Mathematical Principles of
Natural Philosophy and His System of the World, trans. A. Motte, rev. F.
Cajori, Z vols. (Berkeley and Los Angeles: University of California
I'ress, 2:569-70.

I \ Yighing the I I 'orld

Cavendish's paper should read like a dissertation
on errors. Errors were, after all, the point at which
he had entered the subject: the first evidence of his
interest in the density of the earth was his criticism
of astronomical observations that ignored the
attraction of mountains.

"To great exactness," Cavendish concluded,
the mean density of the earth is 5.48 times the
density of water. 15 The number was the object of
Cavendish's last experiment, the work of ten
months near the end of his life and the reward for
twenty-five years of tenacity.

In addition to the precision of the technique and to
the knowledge of the earth's interior it offered, there
w as another reason, we believe, why Cav endish did
this last major experiment. He had long since
completed the principal researches of his middle
years: his fundamental researches in electricity,
chemistry, and heat, for which he is famous. By the
end of the eighteenth century, in all of these fields
scientific opinion had moved away from his. But
his experiment on gravity was not subject to the
vagaries of scientific opinion in the same way. This
is not to say that he did not expect criticism. In any
case, he got it.

Despite and, in part, because of his last
experiment. Cavendish had not freed himself from
the claims of the earlier preferred method of
determining the density of the earth. His paper
brought a prompt response from Charles Hutton,
who had done the calculations on the mountain
Shiehallien. The paper in manuscript had been
given to him by Maskelyne, and it had not given
him pleasure. Just a year or so before Cavendish's
paper, Hutton had called attention to his
calculation of the density of the earth from the
Royal Society's experiment. In the article "Earth"
in his Mathematical and Philosophical Dictionary,
Hutton wrote of the density of the earth: "This I
have calculated and deduced from the observations
made by Dr. Maskelyne, Astronomer Royal, at the
mountain Shehallien, in the years 1774, 5, and 6."
In this work he took pride, and then came
Cavendish's paper. On the same day that Hutton
received a second copy of Cavendish's paper from
the Royal Society, he wrote to Cavendish from the
Royal Military Academy in Woolwich where he
worked. He went straight to the point: Cavendish's
"ingenious" paper, which made the density of the

earth 5.48 that of water, concluded with a
paragraph that called attention to the earlier, much
lower value of 4'Az, in the "calculation of which"
he, Hutton, had borne "so great a share." Anyone
who has looked at Hutton's calculations can
sympathize with the plaintive note. Hutton
thought that Cavendish's wording hinted at
inaccuracies in his calculations and seemed to
disparage the Royal Society's experiment. That
experiment, Hutton reminded Cavendish, had
determined not the density of the earth but only
the ratio of that density to the density of the
mountain, 9 to 5. Hutton had supposed that the
density of the mountain is the density of ordinary
stone, 2'/> times that of water, but the actual
density of the mountain was unknown, as Hutton
had pointed out at the time. All that was known
was that Shiehallien was a "mass of stone." Hutton
now believed that the mountain's density was
higher, 3 or even 3'/>, which would then make the
density of the earth "between 5 and 6" — or exactly
where Cavendish had put it — and "probably nearer
the latter number." The Royal Society had not
finished its experiment because it had not
determined the density of stone, Hutton said.
Even now, he hoped that the Society would finish
it, so that "an accurate conclusion, as to the density
of the earth, may be thence obtained.""'

Cavendish believed that he had just drawn
that accurate conclusion and that it was 5.48. Hutton
wanted the density of the earth to depend on what
could never be made precise, the density of "stone."
At the bottom of Hutton's letter to him. Cavendish
drafted a brief response. Without referring to
Hutton's guesswork or excuses, it read: "According
to the experiments made by Dr. Maskelyne on the
attraction of the hill Shiehallien the density of the
earth is 4 l /> times that of water." As to which
density, his or the Society's, was better, Cavendish
did not commit himself, since the Society's
determination was "affected by irregularities whose
quantity I cannot measure." 17

It would have been known to Cavendish
that Hutton had not let go of the problem of

'■■Cavendish, "Experiments to Determine the Uensitv of the
Earth." 284.

"Charles Mutton to Henry Cavendish, 17 Nov. 1798. Cavendish
Mss, New Correspondence.

"Ibid. Cavendish. "Experiments to Determine the Density of
the Earth," 284.

Cavendish

determining the earth's density by the attraction of
mountains. In 1780, two years after his calculation
of the density of the earth, Mutton had published
another paper following up "the great success of
the experiment" on Shiehallien to "determine the
universal attraction of matter," in which he-
repeated his wish that more experiments of the
same kind would be made."* Mutton was to have
his wish but not his way. In 1 <S 1 1 he got John
Play fair to do an investigation of the structure of
the rocks of Shiehallien, and Playfair found the
density of the rocks to be between 2.7 and 2.8.
Since Mutton had guessed 2.5, Playfairs result
raised his calculated density of the earth, but only
slightly, to 4.7. Cavendish's density, 5.48, is much
closer to, within one percent of, the accepted value
today, 5.52. Recall that the Charles Mutton of the
attraction of mountains is the Charles Mutton who
had lost his job as foreign secretary at the Royal
Society in the early 1780s, precipitating a bitter
feud known as the Society's "dissensions."
Maskelyne, who had brought Mutton into the
experiment on the attraction of mountains, had
earlier been a vigorous supporter of Mutton's losing
side in the dissensions. By contrast Cavendish had
given decisive support to Mutton's nemesis, the
Society's president, Joseph Banks. If this unhappy
experience of Mutton at the Royal Society and the
now suspected opposition of Cavendish had
anything to do with his continuing efforts to keep
alive the method of the attraction of mountains as
an alternative to Michell and Cavendish's method,
it is impossible to say now. Mutton had a vested
interest in the earlier method, after all. Mutton
lived to 1825, long enough to know of the high
regard in which Cavendish's experiment was held,
though not long enough for him to know that it was
the ( lavendish experiment.

The Cavendish Experiment

From Paris Cavendish was asked to repeat
his own experiment on the density of the earth.
Blagden w rote to Banks in 1802, telling him of a
conversation with Laplace about Cavendish's
experiment. Me thought that Banks might want to
pass along w hat Laplace had said, w hich was that
the attraction Cavendish measured might involve
electricity as w ell as gravity. Laplace also expressed
the wish that "Mr. Cav. would repeat it /the
experiment/ w ith another body of greater specific

grav ity than lead."' 1 ' So far as we know, if Caven-
dish got the message he never repeated the ex-
periment, but there was no need to; others would
do it, and many times, ever with the desire to
achieve greater accuracy and perfection. Experi-
ments on the attraction of mountains ceased to be
regarded as a precise way to determine the earth's
density, though the attraction of mountains re-
mained a consideration as a source of error in astro-
nomical measurements of location and distance. 20

The Cavendish experiment outlived the
problem of the density of the earth, and that it did
so has to do not only with its precision but as well
with its subject, a fundamental and still enigmatic
force of nature, gravity, with its characteristic-
universal constant. It became the experiment to
determine "big G," as C. V. Boys explained in 1892:

Ow ing to the univ ersal character of the constant C>,
it seems to me to be descending from the sublime
to the ridiculous to describe the object of this /
Cav endish's and now Boys's/ experiment as finding
the mass of die eartli or the mean density of the
earth, or less accurately the w eight of the earth.-' 1

Still today, three hundred years after Newton and
two hundred after Cavendish, gravity is at the center
of physical research. To quote from a recent publi-
cation by contemporary researchers in gravity: The

most important advance in experiments on
gravitation and other delicate measurements was
the introduction of the torsion balance bv Michell
and its use by Cavendish. . . .

'"Charles Hutton, "Calculations to Determine at W hat Point in
the Side of a Hill Its Attraction Will he the Greatest, etc," FT 70
(17X0): 1-14. on 3.

"Charles Blagden to Joseph Banks. 1 Apr. 1802, BL Add Mss
33272, pp. 172-73. Notable repetitions include R. Reich. Versuche iiber
die Mittlere Dichtigkeit der h.rde inillrlsl der l)rehv?age (Freiburg, 1838):
Francis Baily, Memoirs of the IRoyall Astronomical Society of London 14
(1X4.S): 1-120: C. V. Boys. "On the Newtonian Constant of
Gravitation," /T1860895): 1-72.

-'"For example. John Henry Pratt's criticism of the observations
taken in the Great Indian Survey in the middle of the nineteenth
century owing to the neglect of the attraction of the Himalayas and
his own calculation of their attraction: Mott T. Greene, Geology in the
Nineteenth Century: Changing Views of a Changing World (Ithaca and
London: Cornell University Press. 1982), 238- 43.

-'' Boys is quoted by ( Clotfelter on the shift in interest in ( Cavendish's
experiment: " The ( Cavendish Experiment as ( Cavendish Knew It." 211.
Boys first calculated G from the Cavendish experiment, anil then from
it he calculated the mean density of the earth. Conv ersely to obtain (I
from the density of the earth. Boys said he could have recalculated the
attraction of the earth by viewing it as an ellipsoid of similar shells of
equal density, which is the way J. 1 1. Poynting had calculated it in 18<^.
Boys recommended using a room with a more uniform temperature
than Oxford's, a detail that will be appreciated by anyone who knows
Oxford and the uniform chill of its rooms. His accuracy w as very great,
despite his room; he believed that his C had an accuracy of 1 in 10.000.

Copyrighted maM

Weighing the World

341

PLAIT. XIV. Plan of Glapham. This detail from "Batten's Plan of
Clapham" of 1827 shows the shape of Cavendish's house seventeen
years after his death and twenty-nine years after his experiment on
the density of the earth. To the right of the house, it shows an out-
building about 58 by 26 feet, the long dimension of w hich is oriented
in the east-west direction. Cavendish refers to the arm of his appara-
tus aligned in the magnetic east-west, which suggests that this out-
building is w here Cavendish performed the experiment. This reason-
ing is given, and this detail from Batten's plan is reproduced, in P. K
Titchmarsh, " The Michcll-Cavcndish Experiment," The School Sci-
ence Review, no. 162 (March 1966): 521-22.

It has been the basis of all the most significant
experiments on gravitation ever since.- 2

That is why Cavendish's experiment became the
Cavendish experiment.

Cavendish initiated no more ambitious pro-
grams of research. His only publication after his paper
on the density of the earth came some ten years later,
a short paper on a typical concern, a way to improve
the accuracy of astronomical instruments. 2 ' Except for
going regularly to meetings of the Royal Society and
to other meetings of scientific men, he stayed
home, which is where he had done his experiment
on the density of the earth. Long after Cavendish's
death, Clapham Common neighbors would point to
the house and tell their children that that was
where the world was weighed. Although Cavendish
was not the first owner of that house, after his
death it was known as the Cavendish house. 1 *

The world of science has changed. John
Henry Poynting, for his repetition of the Cavendish
experiment a hundred years later, received a grant
from the Royal Society, and he was given a workplace
in an institute, in the laboratory at Cambridge named
after Henry Cavendish. Clerk Maxwell, the first

director of the Cavendish Laboratory, gave Poynting
permission to do the experiment. 25 Poynting's
repetition of the Cavendish experiment belongs to
physics after it had become an established discipline
with its principal home in places of higher learning,
complete with institutes, directors, and grants.
Cavendish did his experiment at home.

In connection with the determination of the
density of the earth, Cavendish brought into his home
one person from the outside, George Cilpin, not a
member of the Royal Society but its clerk. Replacing
Cavendish at the telescope, Cilpin made the last two
experiments. He was no doubt cast by Cavendish as
a detector of error as well as a confirming witness.

Cavendish's weighing of the world had a
precedent in William Cilbert's experiments on
magnetism two hundred years earlier, reported in
his De magnete, the classic work of early experi-
mental physics. "By forming a little load-stone into
the shape of the earth," Cilbert "found the
properties of the whole earth, in that little body,"
on which he could experiment at will. 26 Mountains
high on the earth and open to the sky could deflect
weights, and the earth could be weighed that way,

- J A. II. (look. "Experiments on Gravitation," in Three Hundred
Years of Gravitation, ed. S. W. Haw king and W. Israel (Cambridge:
Cambridge University Press, 1987), 51-79. on 52. Appropriately.
Cook talks of the Cavendish experiment only in connection w ith G
and not with the density of the earth. Only recently, he says, has the
accuracy of G been improved upon over what can be obtained from
Cavendish's own experiment, and although in the study of materials
we can achieve an accuracy of 1 part in 10'-. we still know G only to
about 1 part in 10'. Cook speaks of the use of the torsion balance in
electrostatics as well as in gravitation. In a footnote in his paper of
1798, on p. 250. Cavendish too referred to Coulomb, who had used
an apparatus of the same kind for measuring small electric and
magnetic attractions. Cavendish said that "Mr. Michell informed me
of his intention of making this experiment, and of the method he
intended to use, before the publication of any of Mr. Coulomb's
experiments." Prom what Cavendish knew of Michell, the torsion
balance was independently invented by him and by Coulomb.
Coulomb's biographer C. Stewart Gillmor discusses the question of
priority in Coulomb anrt the Evolution (if Physics and Engineering in
Eig/iteenth-Century France (Princeton, 1971 ), 165-65.

''Henry Cavendish. "On an Improvement in the Manner of
Dividing Astronomical Instruments," /'/' 99 (18091: 221-51.

24 According to hearsay. Cavendish weighed the world not in his
house proper but in an outbuilding in his garden. For our discussion, it
does not really matter: Cavendish weighed the world at home.

B J. II. Poynting, "On a Determination of the Mean Density of
the liarth and the Gravitation Constant by Means of the Common
Balance." FT 182 (1892): 565-656, on 565-66. It all conies together:
Poynting did this experiment in Cavendish's spirit, to improve upon
Cavendish's accuracy, in the Cavendish Laboratory directed by
Maxwell, who edited Henry Cavendish's electrical paper and whose
edition is reprinted as the first volume of Cav endish's Scientific Papers.

'' Kenelm Digby, 1645. quoted in the "Biographical Memoir." in
William Gilbert, De magnete, 1600. trans P. Fleury Mottelay (1895; New
York: Dov er reprint. 1958), xv iii.

342

Cavendish

and Cavendish had worked with the astronomers
who weighed it that way, but his own experiment
was better suited to his temperament. With it he
did not need to go out into the world to know it; he
could know it and know it more precisely by
staying home and manipulating his apparatus and
reasoning from universal principles. The world
came to Cavendish. (Another way of viewing it is
that Henry Cavendish was a Cavendish, and the
Cavendishes liked to stay home and let the world
come to them.) Cavendish stayed at home, inside
of a building, looking inside of a room and through
a slit in a ease inside of which was the world — his
world, on his terms.

It has been noted that while there is much
talk about the effect of the scientist's personality
on science, there is little of the other, perhaps more
profound, effect of science on the personality.-' 7 In
Cavendish we see both effects, mutually reinforcing.
From the beginning Cavendish turned away from
what he found difficult, ordinary society, and toward
nature and its understanding through science, and
through science he came into a society he found, if
not comfortable, to his liking. Those traits that in
his casual contact with people gave rise to anecdotes
about his eccentricities were precisely the traits that
in his scientific work made him extraordinary. To do
science. Cavendish did not have to overcome his
extreme diffidence; he had only to adapt it to
science. The experiment on the density of the earth
is arguably not Cavendish's most important experi-
ment, but if it is looked at for what it reveals about
the experimenter — as if it were a diary, which he
did not keep, or a formal portrait, which he did not
allow — it is the most expressiv e of his experiments.

No preliminary' manuscripts connected with
the experiment on the earth's density have sur-
vived or, anyway, surfaced. - x That cannot be said of
any other important experiment by Cavendish.
The quirky history of his papers after his death
enabled Cavendish this time to exclude not only
his contemporaries but his biographers as well.
With his paper of 1798, lie appeared before the
world finished, complete.

The man who weighed the world was a se-
cluded figure and yet a constant companion of men
of science, posing and symbolizing the historian's
problem of the relationship of the individual person
or event to collective actions. Through the experi-
ment on the density of the earth. Cavendish worked

out his private destiny, and at the same time he was
the able representative of a general development in
science, the drive for precision, which began in his
time and which has gathered force ever since. 29
Cavendish worked secluded at Clapham Common,
but his experiment belonged to a public world of
established scientific problems, instrumental possi-
bilities, and interested, qualified parties. 50

The Cavendish experiment did more than
provide precise information about the earth; it
became an ideal of scientific practice. Cavendish
was not a "geophysicist" or a "physicist" but a
universal natural philosopher in a time when the
discipline of physics was just emerging. In
Germany, for example, the early physics journal
was the Anna/en der Physik utid Chemie. When after
eight years of operation its founder, F. A. C. Gren,
died — this was in 1798, the year of Cavendish's
experiment — its new editor, L. W. Gilbert, wrote a
foreword to the new beginning under him, and
under the new, restricted title, Amialen der Physik.
Kxplaining that the richest v ein of material for his
journal would continue to be mined from foreign
sources, Gilbert trusted that in his journal, work by
the best physicists in Germany would stand side by-
side with the best work from abroad, such as
Cavendish's experiment on the density of the earth
with its wonderful "exactness."" Cavendish's

27 Philip J. Hilts. Scientific Temperaments: Three Lives in
Contemporary Science (New York: Simon and Schuster. 19X2), 1 1.

-"One manuscript should be mentioned nevertheless. Cavendish
experimentally determined what we would call the moduli of bend
and tw ist for w ires and glass tubes by comparing the vibrations of his
tw isting apparatus w ith the v ibrations of a simple seconds pendulum,
lie tried wires of different materials, iron, copper, silver, and brass,
suspending from them rods of wood, brass, and zinc. His undated
experiments on twist show Cavendish's interest in torsion, but they
are not necessary for his experiment with Michell's torsion balance.
"Kxper. on Tw isting of W ire Tried by the Time of Vibration," Henry
Cavendish Mss Vl(b). 22.

-"'It was only at the end of the eighteenth century that precision
measurement "becomes a really essential factor in scientific progress."
Maurice Daumas, "Precision of Measurement and Physical and
Chemical Research in the Eighteenth Century," in A. C. Crombie, ed..
Scientific Change... (New York: Basic Books, 1963). 418-30. on 429.

'"'The interested parties were experimenters, instrument-
makers, astronomers, mathematicians, and the practical "lesser" men
whose collaboration is the subject of E. (>. R. 'Taylor, The
Mathematical Practitioners of Hanoverian England, 1114-1640 (Cam-
bridge, 1966).

"L. W. Gilbert, "Vorrede," Annalen der Physik 1 (1799):
unnumbered page in the three-page foreword. 'This quotation
connects Henry Cavendish with the starting point of Christa
Jungnickel and Russell McCormmach, Intellectual Mastery of Nature, 2
vols. (Chicago: Chicago I'niversity Press, 1986) 1: 35.

Copy rig hi et

Weighing the World

experiment, in this sense, belongs to the history of
physics of the nineteenth and tw entieth eenturies.

In the usual biographical sense, of course,
Cavendish's experiment belonged exactly to the
time when it was made. The experiment made
history, but there was no history in it. We will
explain. Cavendish always kept a number of clocks
going. He compared them, used them in his
researches, and consulted them in his daily life
(and, by the standard portrait, was ruled by them).
Time for him was a measure of events, but it was
not a generator of events, a point of view which
more than his phlogistic ideas or anything else
places him within a certain framework. The nature
of his interest in time is shown by his study of the
Hindoo civil year; based on astronomical
periodicities, the civil year implied nothing new in
the world. In his work on heat, Cavendish arrived
at the first law of thermodynamics, but he did not
state the second, which implies the physical
directionality of time. He rarely dated his experi-
ments, nor was there need to, given the kind of
questions he asked of nature. His observations in
the field led him to the chemistry of minerals but
not to ideas about an earth evolving in time. His
last published experiment, the subject of this
chapter, replaced the static chemical balance with
the torsion balance, but it was a balance all the
same. The secular changes in his readings during
the weighing of the world were not a datum but an
erratum. This last experiment of the master ex-
perimenter was one of the great dynamic experi-
ments of the passing age, and it was in the
vanguard of the emerging physics of precision, but
it did not point in the direction of the new history
of the earth with its dynamic idea of time. The
experiment had been conceived in the period of
Cavendish's work, the 1760s to the 1780s. That
work was complete unto itself, and it was only by
chance that the experiment had had to wait until
the end of the century. 52 It was then, just as
Cavendish was doing the experiment, that
scientists working in the physical and life sciences
began fully to appreciate the scale of time and the
related significance of development over time. From
the middle of the eighteenth century, of course,
Buffon, Kant, and other scientific thinkers had
proposed impressive, comprehensive conceptions
of nature in which the world evolved over eons in
concordance with Newtonian principles, but it

343

would be the scientists who came after Cavendish
who would work so intensively w ithin a new world
view strongly imprinted by history." The Caven-
dish experiment was a replication in the laboratory
of the workings of the solar system, and as such it
belonged to the classical harmony of a certain
Newtonian world view. The system of weights that
Cavendish observed was dynamic but it was stable
too. The same could be said of the Cavendish ideal
of the social and political world, which was also
passing into history.- 54

In one other respect, Cavendish's last ex-
periment might seem to place him in an age of
science about to be superseded. A leading theme
of the physical sciences of the nineteenth century
was the interconversion of forces. This, however,
unlike the historical perspective, would probably
have fitted into Cavendish's view of nature. We
have had occasion to point out Cav endish's under-
standing of forces, which seems to have been fairly
widely held in Britain in the second half of the
eighteenth century. With this understanding, ac-
cording to which the forces surrounding force-
centers alternate between regions of repulsion and
regions of attraction, Cavendish rescued his theory
of electricity from experimental contradiction, as
we have shown. He invoked it again, as we have
also shown, to bring his theory of heat into
agreement with experience. In his theory of the
construction of the magnetic dipping needle, he
analyzed the error of the instrument by assuming
that the "axis /of the needle/ & plane on which it
rolls do not actually touch but are kept from one
/another/ by a repulsive force."" He incorporated

'-'Cavendish's late weighing of the world was a reflection and
comment on the whole of his work. By then new tools and concepts
for directing the energies of experimental science had arrived or
were imminent. The electrical battery was one year away, the wave-
theory of light was two years away, and the atomic theory of
chemistry was only a few years in the future. The relationships
between the forces of nature were established by experiments of a
new kind (exact but not in the first instance inspired by the ideal of
maximum precision). The mathematical development of these
relationships led up to the work of Maxwell, our other marker after
Newton for placing Cavendish in the history of science.

"Stephen Toulmin ami June Goldfield, The Diseovery of Time
(New York: Harper & Row. 1965), 125. 266.

'"•Historians of science today arc inclined to regard the
Newtonian world view as a reflection and rationale of the British
monarchy after the Glorious Revolution. Margaret C. Jacob, The
Cultural Meaning of the Scientific Revolution (Philadelphia: Temple
University Press, 1988). 109. 112, 123.

"Henry Cavendish, "On the Different Construction of Dipping
Needles." Cavendish Mss IX, 40:12-14.

Cavendish

his understanding of forces in his weighing of the
world by anticipating the objection that over the
small distances of his apparatus the gravitational
force might follow a different law. Experience
suggested that this possibility could only occur at
"very minute distances," where the attraction of
cohesion comes into play; he did experiments in
which the lead balls of the apparatus were brought
to rest as close as possible to the sides of the case,
and he found no difference "to be depended on." 36
He examined experimentally the role of heat in
magnetism, 57 electricity, ,s and in nearly every other
part of natural philosophy. I lis theoretical work on
heat led him to a fully general law of the
conservation of force, or energy, the great unifying
law of the doctrine of the interconversion of forces.

One of the earliest of the interconversions to be
discovered was between electricity and chemistry,
and we know that Cavendish took a great interest
in this and came often to the laboratory of the
Royal Institution to witness the work of that avid
developer of electrochemistry, Davy. The pity is
that Cavendish did not live another ten years to
learn of Hans Christian Oersted's discovers" of a
fundamental connection between electricity and
magnetism and to tell us what he made of it.

''Cavendish, "Experiments to Determine the Density of the
Earth," 2H4.

"Henry Cavendish, "Effect of Heat on Magnets," Cavendish
MssIX. .5.

""Henry Cavendish. "Experiments on Electricity." in 'The
Electrical Researches of the Honourable Henry Cavendish, cd. J. ( Maxwell
(Cambridge: Cambridge I Iniversity Press. IK7<». 104-93, on 180-81.

Copy rig hlM matsrr

CHAPTER 8

^ast Years

The Duchess and the Philosopher

For most of Henry Cavendish's adult life, the
head of the Cavendish family was the fifth duke of
Devonshire, the first of the dukes of Devonshire to
turn his back on politics. I Ie had that much in
common with Henry Cavendish, as he did these
traits: he was intelligent, withdrawn, reclusive, long
lived, and, perhaps, he "had something of the
questioning way of Mr /Henry/ Cavendish." 1 He
understood that his distinction was not at all
personal but hereditary, and therefore — here he
departed from Henry — no individual exertion was
required of him. Told he was going to receive the
blue ribbon of the Carter, he said he would rather
have a blue greatcoat. His way of dealing with the
world was to avoid it; he stayed in bed until the
middle of the afternoon, when he got up to go to
his club, Brooks's, to gamble all night. He was
dissolute, unfaithful, and, in his dedicated
passivity, fascinating. 2 He disapproved of Henry
Cavendish because "he works." 1 ' When Henry
Cavendish died, the duke took a passing interest in
the inheritance. The duke lived only one year
beyond this working second cousin of his, Henry.

The fifth duke married Ccorgiana Spencer.
Since the marriage was dynastic, to be eligible they
did not need to be compatible, and they were not,
although they did have one thing in common: like
their great friend Fox, they were both prodigal
gamblers. 4 Otherwise the duchess was the duke's
temperamental opposite, vivacious, enthusiastic,
charming; "her animal spirits were excessive," it
was said of her. The duke, by contrast, was said to
be a simile for winter. 5

Like the Cavendishes, Ccorgiana Spencer's
family had sided with the victorious party in the
Glorious Revolution. Far more interested in
politics than the duke was, the duchess actively
supported the (lost) cause of Fox and his followers,
the old whigs, who opposed Pitt's power and the
new democratizing whigs. She was known as the

queen of London fashion, and at the same time she
had an avid if unfocused interest in music,
literature, history, and science. Like Henry
Cavendish she studied music under Ciardini, who
composed a (somewhat too difficult) piece for her
to play.'' She had a tutor to teach her astronomy
using the globes 7 and another to lecture her on
chemistry and mineralogy/ She and Blagden wrote
to one another with scientific news.'' From abroad
she asked Blagden about "any chemical,
mineralogical, or philosophical novelty," and she
asked him to give her compliments to Cavendish. 1 "
When she and Blagden happened both to be-
abroad and meet, they spent an evening with
"much talk about chemistry & mineralogy." At
another meeting on that trip, they talked with
Gibbon about geography, chemistry, and experi-
ments on nerves: "Dss of Devonshire said she was
quite wild with studies of that nature: asked much
about Mr Cavendish & his pursuits." At yet
another meeting: "much talk with the Dss about Sir
Jos. Banks's meetings, Mr Cavendish, etc." 11 The

'The full quotation is: "Talk with I) about Dss. 10h: had
something of the questioning way of Mr Cavendish." This
comparison, we realize, could as easily refer to the duchess as to the
duke. 4 Sep. 1 794, Blagden Diary, Royal Society. 3:15.

-John Pearson. The Serpen! and the Stag: The Sunn of England's
Powerful and Glamourous Cavendish Family from the Age of Henry the
Eighth to the Present (New York: Holt. Reinhart Cv Winston, 1983),
122-23.

■Francis Bickley, I'he Cavendish Family (London: Constable,
191 1 ), 202.

4 Hugh Stokes. The Devonshire House Cirrle (London: Herbert
Jenkins, 1917), 283-88.

5 Marv Robinson, Heaux e? Helles of England (London: Grolier
Society, n.d.), 301.

•■Bickley, I'he Cavendish Family, 241.

7 I)uchess of Devonshire to Countess Spencer. 11 Jan. 1783,
Devon. Coll., no. 483.

"Charles Blagden to Lord Palmerston, 21 Feb. 1794. draft. Vale.
Osborn Collection, box 63/43.

''Charles Blagden to the duchess of Devonshire. 4 Jan. and 6
Mar. 1794. Devon. Coll.

"'Duchess of Devonshire to Charles Blagden. 4 Mar. 1794.
Blagden Letters, Royal Society, D.61.

""The Diary of Sir Charles Blagden," ed. Gavin De Beer. Notes
and Reeords of the Royal Sonety of London 8 ( 1 950): 65-89. on 76, 80, 83.

346

Cavendish

duchess was nor just making small talk with
Blagden: she called on Cavendish at his house, 1 - and
Cavendish called on her. When Blagden came to see
her at Devonshire House, he found Cavendish there
engaged in scientific talk. ' ^ The duchess and the
philosopher were friends.

Coinage of the Realm

In his Sentimental Journey TftrougA France and
Italy, Laurence Sterne wrote that he had in his pocket
"a few king William's shillings as smooth as glass,"
as he explained: "by jingling and rubbing one against
another for seventy years together in one body's
pocket or another's, they are become so much alike
you can scarce distinguish one shilling from another." 14
That accurate description was made in 1768, just five
years before a large recall and recoinage of smooth
gold coins.

In 17cS7 Charles Jenkinson, first earl of
Liverpool, had a committee of the privy council look
into the state of the coins of the kingdom. Liv erpool
was president of the committee, and all the principal
secretaries of state were members plus one man of
science. Banks. For years the committee collected
information. In 1796 Banks gave Liverpool a long list
of questions about the "extravagant waste" of gold in
the wear of coins. 15 Two years later, in 1 798, the
committee appointed Henry Cavendish and Charles
I latchett to make the necessary experiments,
essentially to answer Banks's questions. Soon after
this, the engineer John Rennie was brought in to
make a complete investigation of the mint. Rennie
had worked with Matthew Boulton, who had applied
the steam engine to coin-making in Birmingham.
Boulton had, in fact, set up a mint, which began by
making coins on commission from British territories
and from foreign nations and ended up, in 1 797,
making all of the copper coins for Britain. The
London mint lacked steam among other things, and
Rennie's report on it was scathing. 1 '' .

Money was the standard of the realm: the
"standard coin of every country is the measure of
property in it," Liverpool said. 17 The most energetic
of the masters of the mint up to that time had been
Newton, and the connection of the mint with the
Royal Society had remained substantial: most of the
masters of the mint after Newton had been Fellows
of the Royal Society. Cav endish's work for the mint
belonged to a tradition of scientific service in the
government.

Matthew Boulton and Charles Hatehett both
wrote reports on the coinage, which were given to
Rennie and then to Banks and to Cavendish for
comment. Boulton's report was found useless,
Hatchett's useful, 18 and Cavendish recommended
that the necessary experiments on coins be done
by Hatehett. 1 '' Cavendish was asked to assist, and if
it would help to persuade him (it was not needed),
the king would appoint him a privy councillor. 20

The wider setting of the problem of coinage
was the war. The prospect of a Napoleonic inv asion
in 1797 caused a run on the Bank of Fngland, which
suspended payment of its notes in gold. Up to then
paper money had been of high denomination only,
and traders and wage-earners rarely used it, but now
one and two pound notes were introduced. Although
as it turned out, the last year that new coinage was
minted on any scale was 1798,-' 1 it was thought
important to know how to make gold coins so that
they would not wear away so fast.-'-'

' 'Once when she called on Cavendish, his servant told her he
was not well, and she asked Blagden to find out how he was. Sir
Charles Blagden to Sir Joseph Hanks. 1 Aug. 1795. BL Add Mss
33,272, p. 143. It was not an excuse; Blagden called on Cavendish
later that month and found him "decaying: his forehead healing not
kindly." 27 Aug. 17%, Blagden Diary. Royal Society, .V.67.

1 M Sep. 17 C M, Blagden Diary, Royal Society. 3:14. The duchess
proposed that Cavendish "shew extracts from Js de Physique." On
27 Nov. 1794. Blagden again came across Cav endish at the duchess's:
ibid., hack p. 33.

'■"Laurence Sterne. A Sentimental Journey Through France and Italy,
first published in 176K: introduction by V. Woolf (London: Milford.
1951), 165-66.

■U nsigned memorandum by Sir Joseph Banks to the second
earl of Liverpool, /1 796/. in Liverpool Papers. BL Add Mss 3K422.
v ol. 233, ff. 320-24, on 321-22.

" J. C. Chaston, "Wear Resistance of Cold Alloys for Coinage:
An Karly Example of Contract Research," Gold Bulletin 7 (1974):
108-12, on 108. John Craig. " The Royal Society and the Royal
Mint," Notes anil Records of the Royal Society 19 (1964): 156-67, on
161-63. Beginning in 1H07 Boulton installed steam power in a new
mint in London.

'""Heads of So Much of Lord Liv erpool's Speech at the Council
Board . . . Respecting the Coins and Mint of this Kingdom . . .,"
Liverpool Papers. BL Add Mss 3K423. vol. 234. ff. 402-3.

'"Lord Liverpool to Sir Joseph Banks, 10 May 179H. copy,
BM(\H). DTC 3 279-HO.

'''Henry Cavendish to Sir Joseph Banks. 2H July and 6 Aug.
179X. copy. BM(MI), DTC 3. 19-20, 29. Lord Liverpool to Sir
Joseph Banks. 13 Feb. 1799. copy, ibid., 195-96. A report was also
given, on Cavendish's urging. In A. Robertson, an Oxford scholar
who did research on coinage; Robertson's report was delivered and
read by Cavendish, to whom Liverpool gave his thanks on 12 Apr.
1799: Liverpool Papers. BL Add Mss. 3X424, vol. 235, f. 55.

: "Lord Liverpool to Joseph Banks, 7 Julv 1798, copy, BM(NII).
DTC 3 19-20.

-'John Clapham, The Hank of England. A History. 2 vols.
(Cambridge: Cambridge I nivcrsity Press. 1945) 2:2—1. 7-9.

--Banks's list of questions about coinage to Lord Liver-
pool, f. 321.

CopyrighliM mater

Last Years

PLATE X\'. Coinage Apparatus. This drawing shows the apparatus designed by Cavendish for examining the wear of coins; it was built for him by
John Cuthbertson. In it twenty-eight pairs of eoins are pressed and rubbed together by turning the crank. Each pair of coins is separately weighted,
and the frames holding the top and bottom coins vibrate at different rates to reduce grooving. Charles Hatchctt, "Experiments and Observations
on the Various Alloys, on the Specific Gravity, and on the Comparative Wear of Cold. Being the Substance of a Report Made to the Right 1 lon-
ourable the Lords of the Committee of Privy Council...," Philosophical Transactions 93 ( 1803): end of volume.

Newton and Folkes had understood that
silver was the standard coinage, coins made of other
metal or notes having only conventional value, but
for most of the eighteenth century gold had been
the de facto standard.-' The experiments Cavendish
laid out were to decide what kind of gold coin
would best resist wear. They were lengthy, since
they had to replicate the wearing down of coins in
Laurence Sterne's pocket. The punishing machines
were designed by Cavendish and built by the
instrument-maker John Cuthbertson, in whose house
the experiments were carried out. One machine was
a rotating oak container in which a large number of
pieces of gold of different ductility were agitated.- 4
Another, more complex machine, pressed coins
together and moved them laterally across one
another. To Cavendish the weigher, it was obvious
that the measure of wear was the loss of weight of
the coins. In another part of the experiment,
thirteen gold alloys were hammered and rolled.

Hatchett wrote the report for the privy council
committee on coins, confirming the "practice of
the moneyers" and also bringing forward "many
points very interesting to Science that are quite
new." 25 Cavendish prefaced the report with a letter
explaining that Hatchett was the sole author because
he had done the experiments and was best able to
give an account of them. The experiments were
done with "great judgement & accuracy, & in the
manner which to both of us seemed best adapted to
the object proposed," Cavendish said. 26 He then

-'"Heads of So Much of Lord Liverpool's Speech," ff. 402-9.

"Charles Hatchett to Sir Joseph Banks, 14 Mar. 1800, Bl. Add
Mss 33,980, f. 225.

»Sir Joseph Banks to Charles Jenkinson. 11 May 1801, BL Add
Mss 38424. ff. 158-59. The report, addressed to Lord Liverpool and
the select committee for coins, signed by Hatchett. 28 Apt. 1801: BL
Add Mss 38426. The title of the report of the experiments, beginning
on f. 25. is "Experiments and Observations on the Various Alloys, on
the Specific Gravity, and on the Comparative Wear of Gold."

^Cavendish to the Privy Council Committee for Coins, pre-
facing llatchett's report signed 28 Apr. 1801, BL Add Mss 38426, f. 1.

348

Cavendish

made an appeal to the government to let I latchett
publish his results and not keep them a government
secret. Nothing in these experiments, he explained,
"requires to be kept secret" and no "had effect"
could come of their publication.- 7 Hatchetts
abridged paper was read to the Royal Society and
published in the Philosophical Transactions. "At the
request of Mr. Cavendish," Hatchett wrote, " I
have written the following account; but I should be
highly unjust and ungrateful to that gentleman, did
I not here publicly acknowledge how great a
portion truly belongs to him." The machines and
dies were "entirely contrived" by him. 2 *

Then in his early thirties, Hatchett had
published chemical analyses in the Philosophical
Transactions, and he would go on to discover a new
element. I le was using Lavoisier's new nomenclature
of "oxyde,"-"' and the giants of the recent great past
of British chemistry looked ancient to him. On a
journey in Kngland and Scotland in 17%, he met
Black, "a thin old man," and Brownrigg, "the
oldest pupil of Boerhaave now living,'" 1 " and soon
after he collaborated with Cavendish, who
probably seemed another (albeit very vigorous)
ancient. Hatchett was elected to the Royal Society
in 1797, and Cavendish took an interest in his
election to the Society's dining club in 1802. They
w ere both managers of the Royal Institution, where
they saw one another frequently. Hatchetts field
was chemistry and mineralogy, which was the basis
of his friendship with Cavendish and their
collaboration on experiments. 31 Hatchett was one
of a number of young chemists and natural
philosophers w ith w hom Cavendish was scientifically
close tow ard the end of his life.

The experiment on coins dragged on for
two or three years, and when it was done, the
results turned out not to be particularly useful to
the government. 32 It was superb science all the
same. I latchett said correctly that know ledge of
metal alloys had not "kept pace with the rapid
progress of modern chemistry" and had hardly
gone beyond what Pliny and the ancients knew. 33
According to a recent commentator, "the grasp
shown by Cavendish of the complex nature of wear
was masterly; it could have been studied with
advantage by investigators a century later." 34

Weighing and coinage had been inseparable
over the ages; traditionally the main interest of
governments in reliable weights was coinage, as

the names of currency indicate, the British
"pound," for example." It was self-evident that
Britain's most celebrated weigher, the man who
had just weighed the world, would be chosen as
the weigher of gold coins. For Cavendish, it was
public sen ice as usual.

Royal Institution

For decades Cavendish served two
institutions, the Royal Society and the British
Museum, and in the last decade of his life, for
several years, he served a third, the Royal
Institution. This latter was the brain child of a
soldier of fortune born in America, Benjamin
Thompson, or as he was then better known. Count
Rumford. Having served on the losing side in the
American Revolution, Rumford retired from the
British army to become a Massachusetts Yankee at
the court of the elector of Bavaria, where he rose to
the head of the army and acquired his title, count.
His Yankee ingenuity found ample outlet in
feeding, clothing, and warming the army of Bavaria
and the poor of Munich. There in addition to
making mechanical inventions, he did experiments
on the principles of heat and conceived of the idea
of an institution of mechanics and heat in London,
which became the Royal Institution. In 1798
Rumford came to London, where his ideas on

-'Henry Cavendish to Charles Hatchett, I S Oct. IK02; this letter
was enclosed in one to Banks by Hatchett. in which Hatchett said
that Lord Liverpool was satisfied with Cavendish's opinion on the
publishablc nature of the material. Banks gave his approval too.
w hich he sent to Lord Liverpool: Charles I latchett to Sir Joseph
Banks. 24 Oct. 1H02. Hatchett and Cavendish's desire to see the
experiments published w as first put to Lord Liverpool by Sir Joseph
Banks on 21 Aug. 1801, BL Add Mss iK424. f. 160.

Z8 Charles Hatchett. "Experiments and Observations on the
Various Alloys, on the Specific Gravity, and on the Comparative Wear
of Gold. Being the Substance of a Report Made to the Right
Honourable the Lords of the Committee of Privy Council . . .," I'T
93 (1803): 43-194, on 45.

-"'Charles Hatchett. The Hatchett Diary: A lour Through the
Counties of England and Scotland in 1796 Visiting Their Mines and
Manufacture . cd. A Raistrick (Truro: I). Bradford Barton. 1%7), 41.

'"Ibid, 84, 104.

'■ They collaborated on platina, evidently in 1799, as recorded in
Cavendish's "W hite Book." p. 129, and in a letter from Cavendish to
Hatchett enclosed between pp. b.5 and 66, thanking Hatchett for
experiments he made on platina.

'-' The experiments showed that there was really nothing much
to be gained by substituting smooth coins for embossed ones or a
harder or softer alloy for the standard twenty-two carat gold. ( lhaston,
"Wear Resistance." 1 12.

"Hatchett, "Experiments and Observations," 193.

"Chaston, "Wear Resistance." 112.

"Bruno Kisch, Stales and Weights: A Historical Outline (New
Haven: Vale University Press, 1965), 6, 9.

Last Years

349

kitchens and heating had preceded him, put in
place at the Foundling Hospital by the professional
philanthropist Thomas Bernard. Bernard and the
recently formed Bettering Society asked Rumford
to draw up a plan for an institution to teach
applications of science and spread knowledge of
inventions. Another variant on the Baconian plan,
Rumford's scheme nearly came off. He organized a
subscription whereby a person who gave fifty
guineas or more became a perpetual proprietor, and
one who gave less received a lesser title. There was
a quick response, and in 1799 the Royal Institution
was launched. 5 ''

The original proprietors were not men of
science, with the major exception of Banks. The
meeting at which the new institution was founded
was held at Banks's house, which gave it an
unofficial imprimatur of the Royal Society. The
second man of science was Cavendish," who paid
his fifty guineas almost a year later, in early 1800.
The duke of Devonshire paid at the same time,
the Cavendishes joining only when the institution
was clearly respectable. Their relative the earl of
Bessborough, who was already a member, had just
become a manager of the Institution. It was just
about this time that the first lecture was given in a
house on Albemarle Street; the Royal Institution
w as off and running. 38

Cavendish had long been a subscriber to
the Society of Arts, which like the Royal Institution
fostered invention. Cavendish took no part in the
affairs of the Society of Arts, but in those of the
Royal Institution he became fully involved. The
obvious difference between the two institutions
was the strong connection with science in the Royal
Institution. The month after Cavendish subscribed,
a standing committee of science was established to
oversee the syllabus and the philosophical experi-
ments and to communicate worthy experiments to
the sister institution, the Royal Society. Cavendish
was an original member of this committee along
with Maskelyne, Blagden, Hatchett, and several
others, all Fellows of the Royal Society. 39 The
governing body of the institution was nine managers,
elected from the proprietors initially, and Cavendish
promptly became a manager as well. 40 The meetings
of the managers were irregular but frequent; as a
rule only three or four managers turned up along
with the secretary and treasurer. Banks, Hatchett,
and two or three others came often, but Cavendish

with his typical all-or-nothing commitment became
the most faithful attender. The first years of the in-
stitution were chaotic owing to Rumford's dictatorial
methods. When the first scientific lecturer, Thomas
Carnett, acted independently, Rumford got the
managers to appoint a committee of three to
supervise the syllabus in the future: the triumvirate
was Rumford, Cavendish, and Banks. 4 ' In this and
other ways, Rumford leaned on Cavendish and Banks
to establish his authority and get what he w anted.

But Rumford did not get the practical
institution he wanted. His plans for instructing the
lower classes were opposed by the managers, and
his plans for an exhibition of inventions were
opposed by the manufacturers. But because of
Rumford's drive, the institution existed in the first
place, and it began functioning even as the
workmen were expanding its house to make it
suited for lectures and experiments. Important
changes of staff were made in 1801. On Banks's
recommendation, the original senior lecturer,
Carnett, was replaced by Thomas Young, and on
Rumford's recommendation, Humphry Davy was
hired as assistant lecturer in chemistry. Davy, more
than anyone, insured the scientific eminence of the
institution by attracting fashionable London to his
public lectures on science and by doing outstanding
chemical research. 42 Rumford's presence at the
institution was erratic, and in 1802 this restless man

,6 K. I). C. Vernon, The Foundation and Early Years of the Royal
Institution (London: Royal Institution. 1463). 1—4. W. J. Sparrow. Knight
of the White Eag/e (London: Hutchinson, 1964), 109-10. Sanborn C.
Brown. "Thompson, Benjamin (Count Rumford)." DSB 13:350-52.

'"Vernon. Foundation. 4.

'"Cavendish became a proprietor on 10 Feb. 1800. The
managers, at their meeting on 17 Feb., said that the Royal Institution
was "now established on a Basis so firm & respectable, that no Doubt
can be entertained of its Success." The first lecture at the Royal
Institution was announced for 4 Mar. 1800: Royal Institution of Great
Britain. The Archives of the Royal Institution of (ireat Britain in Facsimile.
Minutes of Managers' Meetings 1799-1900. vols. 1 and 1 (in one volume),
ed. F. Grecnaway (Ilkley, Yorkshire: published in association with the
Royal Institution of Great Britain by the Scolar Press Limited. 1471 ).

l 'Kntry for 31 Mar. 1800, Minutes of the Meetings of Managers,
Royal Institution Archive, pp. .VI— 41. The- other six members were
Major Rennell. Joseph Planta, K. Whitakcr Gray, J. Yincc. and
William Parish: the last two were professors of experimental
philosophy and of chemistry at Cambridge. Maskelyne turned down
the appointment because he was too busy.

*'Hc was elected at the annual meeting of proprietors on 1 May
1800. pantry for 5 May 1800. Minutes of the Meetings of Managers,
Royal Institution, p. 70.

41 Entry for 31 Mar. 1800, Minutes of the Meetings of Managers.
Royal Institution. Vernon, Foundation. 18.

4 -'\'ernon, Foundation, 24, 29.

350

Cavendish

left it for good. The soon-to-appear movement for
mechanics institutes would take up the cause of
technical education; the Royal Institution was set
on its course of scientific achievement.

The year after Rumford left, in 1803, the sci-
entific committee was reappointed, with Cavendish,
Banks, and I latchett on it again. 4 ' Later in the year
the committee recommended Thomas Young's
successor, John Dalton. 44 Cavendish did not live
quite long enough to see the arrival of the greatest
of all the scientists to work in the Royal Institution,
Michael Faraday. 45

We have no idea what Cavendish thought of
the practical plans for the Royal Institution, but we
do know that he wanted the closest possible coopera-
tion between it and the Royal Society. It was he
who seconded Rumford's motion to direct the
secretaries of the two institutions to keep one
another regularly informed. 4 '' Cavendish took an
interest in the scientific lectures, as was required of
him by his appointment to the scientific committee;
among his papers is a letter from Thomas Young
asking his opinion on something about gearvvork he
intended to put in his syllabus, and in his lectures
he gives an explanation of halos around the sun
that ( lavendish suggested to him. 47 Cavendish's main
interest, however, was not in the lectures but in the
experiments at the Institution. He, Banks, and
I latchett were in charge of the scientific research
in the laboratory, 4 * and through the last year of his
life Cavendish witnessed experiments and assisted
in them. 41 '

The Royal Institution was, in particular, an
institution of heat, the field in which Rumford was
scientifically preeminent. He had been publishing
his researches on heat in the Philosophical Transactions
since 1786, and in a paper read before the Royal
Society in 1798, the year he moved to London, he
wrote: "The effects produced in the world by the
agency of Heat are probably just as extensive, and
quite as important, as those which are owing to the
tendency of the particles of matter towards each
other; and there is no doubt but its operations are,
in all cases, determined by law s equally immutable." 50
One of Rumford's readers was Cavendish, who did
not need to be told that heat is as ubiquitous and
important as gravity. Rumford started out believing
that heat is a fluid but had since corrected his
error. 51 It was fortunate that he did, for his view of
heat as motion was responsible for his far-sighted

selection of Humphry Davy as chemical lecturer.
In 1799 the twenty-one year-old Davy published a
tract 52 that came to Rumford's notice; Rumford
recognized ideas similar to his on the nature of
heat, and their author w as offered the job. 55 Oarnett
had studied under Black at Kdinburgh University,
and in his lectures at the Royal Institution he gave
full treatment to Black's theory of "latent heat" and
used the word "caloric" throughout. This was just
after Rumford believed he had proven that there is
no such thing as caloric and that heat is motion.
Rumford and Oarnett had a falling out when
Oarnett published his syllabuses without approval,
but Rumford may have been dissatisfied with the
contents of Oarnett's lectures as well. 54 Like Davy,

■"Entry for 26 May 1803, Minutes of the Meetings of Managers,
Royal Institution, pp 137-38.

■"Kntry for 5 Sep. 1803. Minutes of the Meetings of Managers.
Royal Institution, p. 151.

45 Thrce years after Cavendish's death, in 1813, Davy received
from Faraday a copy of the notes Faraday took of Davy's lectures at
the Royal Institution. This was the statt of Faraday's association with
the Institution.

■"•'I'he Royal Institution began its own journal. The motion that
Cavendish seconded called for the Royal Society to inform the Royal
Institution of papers read at its meetings that were suitable for the
Royal Institution's journal. It also required that an earlier resolution
of the Royal Institution he communicated to the Royal Society; this
resolution concerned the duty of the scientific committee to
communicate discoveries to the Royal Society. Entry for 5 Apr. 1802.
Minutes of the Meetings of Managers, Royal Institution, p. 260.

■"Thomas Young to I lenry Cavendish, 3 Sep. 1K01, enclosed in a
paper. "On the Shape of the Teeth in Rack Work." Cavendish Mss.
YI(b), 31. In Thomas Young's A Syllabus of a Course of Lectures on
Natural and Experimental Philosophy (London. 18021. paragraph 179,
Vuing acknowledged Cavendish for the demonstration. Joseph
I. armor's comment in Cavendish, AW. Pap. 2: 410. Thomas Young, A
Course of Lectures on Natural Philosophy anil the Mechanical Arts, 2 vols.
(London. 1807) 2:308.

"Vernon, Foundation, 27.

• 'John Davy, Memoirs of the Life of Sir Humphry Davy, Hart. 2
vols. (London. 1836) 1:222.

"■"Count Rumford, "An Inquiry Concerning the Source of the
Heat Which Is Excited by Friction." FT 88 (1798): 80-102; in
Benjamin Thompson, Count Rumford. The Complete Worts of Count
Rumford, vol. I (Boston. 1870). 469-02. on 491.

''Count Rumford. "An Inquiry Concerning the Weight Ascribed
to I leat," PTS9 ( 1 799): 1 79-04.

52 Davy was working in Thomas Beddoes's Pneumatic Institution
at the time. Beddoes included Davy's "Essay on Heat, Light, and the
Combinations of Light" in a collection in 1799, Contributions to
Physical and Medical Knowledge, Principally from the West of England.
David M. Knight. "Davy. Humphry." DSR 3:598-604, on 599.

"George K. Kllis, Memoir of Sir Benjamin Thompson, Count
Rumford... (Philadelphia. 1871). 486.

"Thomas Oarnett. Outlines of a Course of Lectures on Chemistry:
Delivered at the Royal Institution of Great Britain, 1801 (London. 1801 ).
15-16, 30-31. He published at the same time Outlines of a Course of
Lectures on Natural and Experimental Philosophy. Delivered at the Royal
Institution of Great Britain, 1801 (London. 1801). On his studies at
Edinburgh, "The Life of the Author." in Thomas Garnctt. Popular
Lectures on /.oonomia. or The Laws of Animal Life, in Health and Disease
(London. 1804), vi-vii.

Copy rig I ilea

Last Years

Thomas Young, Carnett's replacement, held a view
of heat similar to Rumford's. Davy and Young, in
their lectures at the institution, did not make
(Jarnett's mistake; they made clear their preference
for the vibratory theory of heat. For a time at the
Royal Institution, there was an extraordinary
concentration of upholders of a view of heat that
most practicing scientists believed had long since
been discarded: Rumford, at the head of the
institution, the two science lecturers, Davy and
Young, and the experimentalist of Rumford's inner
circle, Cavendish. Whatever else might be made of
this, it is noteworthy that near the end of his life.
Cavendish was placed in the company of scientists
who broadly agreed with him on the nature of heat,
the subject Cavendish cared most about then. 55

The Royal Institution offered Cavendish a
chance both to serve science publicly and to come
together with gifted young scientists. Two of the
most perceptive biographical accounts of Cavendish
were written by Davy and Young, who knew him
especially from the Royal Institution. "He was
reserved to strangers," Davy said of Cavendish,
"but, when he was familiar, his conversation was
lively, and full of varied information. Upon all
subjects of science he was luminous and profound;
and in discussion wonderfully acute. Even to the
very last week of his life, when he was nearly
seventy-nine, he retained his activity of body, and
all his energy and sagacity of intellect. He was
warmly interested in all new subjects of science."
The exchange, by this account, was not all one way.
Cavendish was invigorated by Davy's work, and
Davy, fifty years his junior, benefitted. 5 ''

Cavendish's presence at the Royal Institu-
tion outlived him. When Davy arrived there in
1801, he was received by Rumford, Cavendish, and
Banks, who promised him any apparatus he wanted
for his experiments. 57 When Cavendish died, his
proprietorship in the Institution was inherited by
Lord George Cavendish, and from him Davy
obtained some of Cavendish's choice chemical
apparatus. Five months after Cavendish's death,
Davy received permission from the managers to
bring this apparatus to the Royal Institution to use-
in experiments and lectures. 58 In his chemical
treatise published two years after Cavendish's
death, Davy made this observation: Cavendish
"carried into his chemical researches a delicacy and
precision, which have never been exceeded." 59

351

Institute of France

When the Institute of France succeeded the
Academy of Sciences of the old regime, the question
of foreign members necessarily came up. Each of
the several classes of the institute proposed
candidates, who were then balloted for at a general
meeting. In foreign scientific circles there was
intense interest in this election, just as there was a
frenzy of lobbying among the French. Foreign
scientists were ranked like race horses, since the
number to be admitted was fixed, at twenty-four.
From Paris in late 1801, Rumford confidentially
informed Banks that he headed the list of ten
foreigners put up by the class of mathematics and
physics. Following him, in order, came Maskelyne,
Cavendish, Herschel, Priestley, Pyotr Simon Pallas,
Alessandro Volta, and three others. Rumford was
himself proposed but in another class.'' 0 Charles
Blagden, who was in Paris as the election grew near
in 1802, wrote to Banks that he was pressing
Cavendish's claims with the scientists he knew in
the Institute, and that he fully expected Cavendish
to be the first elected after the Institute had
elected all its former associates from the Academy.'' 1

"II the theory of heat hail a larger role at the Royal Institution,
it vanished with Rumford. John Dalton. Young's replacement in
1803, was known to hold the fluid theory of heat. G. N. Cantor has
noted the agreement on heat between Rumford. Davy, and Young, in
" Thomas Young's Lectures at the Royal Institution," Notes and
Records of the Royal Society 25 (1970): 87-112, on 90. In contrast to
Garnctt. Young in his lectures at the Royal Institution argued by
analogy with sound to the truth of the vibration theory of heat.
"Newton's opinion." Thomas Young, .1 Course of lectures on Natural
Philosophy unci the Mechanical Arts 2 vols. (London, 1807) 1:148-49.
656. Davy and Young both were particularly concerned to impart in
their lectures the new understanding of radiant heat. With praise for
Rumford's experiments, Davy explained that vibrating particles of
bodies give rise to vibrations in the ether, which in turn
communicate vibrations to particles of bodies. Humphry Davy, A
Syllabus of a Course of Lectures on Chemistry Delivered at the Royal
Institution of Great Britain (London, 1802), 50-54. Davy's first
publication in science, in 1799, which Rumford saw, reported
experiments on the conversion of ice to water lis friction. Davy said:
"It has then been experimentally demonstrated that caloric, or the
matter of heat, does not exist," and that heat is a "peculiar motion,
probably a vibration, of the corpuscles of bodies." The Collected Worts
id .Sir Humphry Davy. Hart., ed. J. Davy, 4 vols. (London, 18.W)
2:13-14. Arnold Thackray, "Dalton, John." DSB 3:537-17. on 541.

*'John I )avy. Memoirs of the Life of Sir Humphry Deny, 1 :222.

""Humphry Davy to Davies (iilbert. 8 Mar. 1801, in John Ayrton
Paris, The life o] Sir Humphry Davy (London, 1831), 78.

The A rchives of the Royal Institution 5 ( 1 975 ): 47, 62 1 26, 1 60.

''''Humphry Davy. Elements of Chemical Philosophy, vol. 1
(London, 1812), 37.

'"Count Rumford to Sir Joseph Banks. 22 Nov. 1801. BL Add
\lss 8099.

6l Sir Charles Blagden to Sir Joseph Banks. 19 June 1802. copy,
BM(NH), DTC 3.170-74.

352

I lis next letter was less certain. Pallas and
Cavendish were tied on the first ballot, and on the
second Pallas came off one vote ahead, as might be
expected, since Pallas was a former associate of the
Academy, and it was understood that the foreign
members of the old Academy would be reelected
to the new Institute. Watt, Volta, and Martin
Hcinrich Klaproth were highly regarded too, which
meant that while Cavendish might be chosen at
the next election, there was "no certainty." In his
favor, Blagden thought, was Napoleon's high
esteem for Cavendish. 62 (Blagden, w ho talked with
Napoleon, was much impressed by his knowledge
and promotion of science.) In his next report,
Blagden said that at the coming election, the
mathematics and physics class intended to present,
first. Cavendish, then Watt, "who ran him pretty
hard," and third Paolo Mascagni, and Volta was not
in the running.'' 1 This time Blagden was proved
right: Cavendish was elected.'' 4 That was not the
end of it, however: among those elected there was
yet another ranking, this one by the French
government. The Institute listed the foreign
members according to their merits in science:
Banks came first, Maskelyne came next because of
his lunar tables for determining longitude/' 5 and
then came Cav endish.

Wealth

Henry Cavendish had big houses, which if
they had been used for conventional purposes
would have incurred big expenses. But Cavendish
did not entertain at home often, and when he did
the company was usually scientific. What his
guests were served was meager and invariable,
according to the stories, one leg of mutton, and that
was it. On one occasion several guests were
expected, and Cavendish's housekeeper complained
to him that one leg of mutton would be in-
sufficient. Cavendish is supposed to have said,
"Well, then, get two." This incident has been
taken as an indication of Cavendish's indifference to
hospitality, 66 but we have another interpretation.
Cavendish formed his social preferences early in
life, never changing them, and that applies, in
particular, to his idea of hospitality. We do not
know w hat Lord Charles prov ided at home, but we
do know that at Cambridge, Henry Cavendish ate
mutton five days of the week. Mutton was
common fare for invited guests; Peter Collinson

Cavendish

asked Martin Koikes, president of the Royal
Society, and his daughter to v isit him and "take a
piece of Mutton w ith me." 67 It has been observed
that from the 1760s, under French influence, the
composition of Fnglish meals changed. Henry
Cavendish continued what he had known as the
usual hospitality from his early years, but now his
guests were perhaps used to more diverse meals
and disappointed if faced with mutton as the only
meat course. Cavendish's hospitality was probably
never that inflexible, in any case. We have the
butcher's and fishmonger's bills from the very end
of his life, and at that time, although leg of mutton
would seem to have been the favorite selection,
Cavendish's housekeeper ordered beef, loin pork,
cod, and oysters, too.'' 8 I lovvev er that may be,
Cavendish did not entertain lav ishly, which is one
reason w hy his wealth was not squandered.

The reason why Henry Cavendish's wealth
existed in the first place was that his father was
wealthy. The great wealth of Lord Charles and
then of Henry Cavendish had three sources: the
family settlements and legacies, without which
thete would have been no wealth at all; financial
prudence; and the public debt of the kingdom.

In addition to the two revolutions we have
discussed, the political and the scientific. Lord
Charles and Henry Cavendish were beneficiaries
of a third, contemporary so-called "revolution," this
one commercial. Certainly one of the major
outcomes of the political revolution was a change
in the relationship between business and govern-
ment. In the past, most government borrowing had
been on the king's word, which had proven
untrustworthy. Parliament took over the responsi-
bility for guaranteeing loans in 1793, from which
time we can properly speak of a "public debt."
The public now had sufficient confidence in the
financial stability of the country to deposit its

''-Sir Charles Blagden to Sir Joseph Banks, 15 Oct. IK02. BM
Add Mss 33272. pp. 204-5.

'■'Sir Charles Blagden to Sir Joseph Banks. 2o Nov. and 6 Dee.
1802, BL Add Mss 33,272, pp. 210-13.

M Sir Charles Blagden to Sir Joseph Banks. 29 Jan. 1803.
Fitzwilliam Museum Library. Perceval 11203.

'■"Sir Charles Blagden to Sir Joseph Banks. 1 Feb. 1803,
Fit/.uilliam Museum Library. I'ercival H206.

"'Wilson. Cavendish. 164.

'■'Peter Collinson to Martin Folkes, n.d.. Folkes
Correspondence, Royal Society. Mss 2.30. vol. 3, No. 3.3.

'"Devon. Coll., box 31: "Vouchers to Mrs Stewarts Household."
at Clapham Common.

Copynghied male

Last Years

money in the Bank of England, which was
designated to handle the public debt in part. 69 As
good land was becoming scarce, public loans
appealed as an alternative source of income, and
there were several to choose from. Two were
offered by trading companies and the rest by the
Bank of England: an enormous loan from the South
Sea Company and a smaller one from the East India
Company; and a substantial loan from the Bank of
England, which also issued a group of annuities.
The latter contained so-called perpetual annuities,
or annuities requiring the government to pay a
fixed rate of interest in perpetuity; and over the
course of the century, most of the public debt — and
most of our Cavendishes' wealth — came to be held
in annuities of this kind. 70

The perpetual annuities owned by the
Cavendishes were controlled by a new policy
introduced in 1751 (on the eve of Henry
Cavendish's majority). The outstanding loans
paying three percent, some through the Bank of
England and some through the exchequer, were
consolidated into a single fund, which was named
the "3 per cent Consolidated Annuities," or "con-
sols" for short. Other annuities paying more than
three percent were united in another fund now
paying only three percent, which were named "3
per cent Reduced Annuities." Both of these funds
were managed by the Bank of England, which paid
out interest, or "dividends," since these annuities
were called "stock." The dividends were paid
twice yearly; in other words, three percent
annuities paid six percent annually, though there
were fluctuations. On stated days the dividends
were drawn and signed for; if the owner of the
stock was not present — of course, the Cavendishes
were never present — through power of attorney
the dividends were deposited with the Bank or the
trading companies. 71

Most of the owners of Bank of England
stock lived in and around London. They were a
varied lot, with many migrants. Huguenots and
Spanish and Portuguese Jews, a good many gentry,
gentlemen, and peers, especially dowagers and
ladies, and corporate bodies such as the colleges of
Cambridge. Increasingly, Bank of England stock
was used to support spinsters and widows and to
meet the demands of marriage settlements. The
number of investors in the eighteenth century was
small, and the majority of these were small

353

investors; most of the stock was held by a few
persons, such as the Cavendishes. And like the
Cavendishes, most investors bought stock and kept
it, regarding it as gilt-edged, and withdrawing only
dividends or else reinvesting them. 7 '

The foundations of Lord Charles ( lavendish's
wealth were modest, his inheritance and his due
according to the marriage settlement, which took
the now familiar form of Bank of England and
South Sea stock. He sold the stock to buy property,
but when he sold the property after his wife's
death he invested in and stayed with the same
kind of investment. By the time of his death fifty-
five years later, by accretion, his investments had
turned into a reasonable fortune. He held what we
would now call a diversified portfolio: between his
South Sea annuities, new and old, and his Bank of
England stock, consols, and reduced three percent
annuities, he was worth 159,200 pounds. This
amount Henry Cavendish inherited in 1783. It did
not contain Elizabeth Cavendish's legacy, which
only appeared in 1784, as an addition to Henry
Cavendish's account. This legacy nearly doubled his
wealth, bringing him 48,000 pounds in mortgages
and 97,100 pounds in consuls and reduced three
percent annuities. In addition, before his father
died, Henry Cavendish held stocks in his own
name, and although by comparison their value was
not a great deal, it was not negligible either, and it
shows that he was independently well off: as of 1776
he had 1,100 pounds in South Sea annuities, and as of
1781 he had 14,000 pounds in reduced three percent
annuities. Thus, in the year after his father's death.
Henry Cavendish held 48,000 pounds in mortgages
and 272,800 in securities (plus possibly a few other
small holdings). 73

''"'The Glorious Revolution had been quickly followed by a
burst of business initiatives, including a great many joint-stock
companies, usually organized around patents. Hanoverian London
was inventive, prosperous, and lull of entrepreneurial energy. John
Carswell, The South Sea Bubble, rev ed. (London: Alan Sutton, 1993),
8. 12, 18-20.

'"Alice Clare Carter, The English Public Debt in the Eighteenth
Century (London: The I listorical Association. 19f>8), 2-9.

71 Eugcn von Philippovich, History of the Rank of England, mid Its
Financial Services to the State, 2d ed„ trans C. Meredith (Washington.
D.C.: Government Printing Office. 1911). 135. John Clapham, The
Rank of England, A History, 2 vols. (Cambridge: Cambridge
I niversity Press, 1945) 2:77. 97-98. CaneT,EnglisA Public Debt, 10.

"Carter, English Public Debt. 18-19. Clapham, Rank of England
1:280-88.

"'Lord Charles Cavendish's stock at the time of his death
consisted of: Bank of Kngland stock. 25,815 pounds; New South Seas
Annuities. 47,000; Reduced },% Annuities, 18.285; Consolidated 39?

354

Cavendish

Wilson gives an anecdote about Cavendish
and his bankers. A large sum of cash, perhaps 80,000
pounds, had accumulated in Cavendish's account,
prompting a banker to call on him to ask what to do
with it. The banker overheard the following
conversation between Cavendish and his serv ant:

"Who is her Who is he? What does he want
with me?"

"He says he is your hanker, and must speak
to you."

When the banker was admitted. Cavendish cried,

"What do you come here for? What do you want
with me?"

The banker explained, and Cav endish responded,

"If it is any trouble to you. I w ill take it out of
your hands. Do not come here to plague me."

"Not the least trouble to us. Sir. not the least; but
we thought you might like some of it to be
invested."

"Well! well! What do you want to do?"

"Perhaps you would like to have forty thousand
pounds inv ested." "Do so! Do so. and don't come
here and trouble me, or I w ill remove it." 74

This story might be taken to illustrate Cavendish's
indifference to practical matters like money in the
bank, and it has been. It as easily illustrates his
annoyance with interruptions. He gave orders
about what to do with his div idends to his bankers,
Messrs. Denne and Co., and in particular to Robert
Snow, who worked there. He was not indifferent to
money, but he did not w ant to be bothered about it
either. His directions would seem to have been
straightforward and consistent: his dividends were
reinvested alternately in four stocks: new and old
South Sea annuities and consols and reduced three
percent annuities. 75 His farm rents went directlv to
his bankers, and all of his business was transacted
through them, and he expected them to know his
wishes and carry them out to the letter. He did not
like to have to repeat himself, especially in person.
1 Ie had enough wealth that he did not have to think
about it, an ideal life that he did not want disturbed.

Cavendish paid bankers to do his banking.
When occasionally he himself acted as a banker-in-
need to his friends and family, who turned to him
for loans, he took little trouble over the business
and gave it even less thought. He did not, for
example, remember if he had received interest on
some money he had lent to a friend; the reason he-

gave for his uncertainty was that "I am not very
regular in my accounts." 7 ''

To the world, Cavendish's vast wealth has
proven as intriguing as his discoveries, as Biot's
well-known epigram testifies: Cavendish was "the
richest of the wise and the wisest of the rich." The
source of his wealth and how and when he came by
it have been stated variously, but that it happened
"suddenly," as Biot said, has been generally assumed.
He made it precise: his uncle, a general overseas,
returned to England in 1773 to find his nephew
neglected by his family, and to make it aright he
left his entire fortune to Henry Cavendish. 77 We
have not found a general from India, who is in any
case unnecessary, since Cavendish's wealth can be
explained otherwise. In 1784, as we have pointed
out, his wealth was already very considerable. A
millionaire when he died twenty-six years later,
Henry Cavendish was already one third of the way
there. From the beginning Blagden tried to control

Annuities, 62,100; anil Old South Sea Annuities. 6,000; which made a
total of 159,200 pounds The next year, 1784, Henry Cavendish's
hank account was augmented by Kli/abeth Cavendish's legacy to
Lord Charles Cavendish, which consisted of: Reduced 3 %
Annuities, 22.100 pounds; Consolidated 3% Annuities, 50,000; and
another group of the latter, 25,000; which made a total of 97,100
pounds. The earl of Hardwicke deposited 916 pounds in his account
in 1783. So to start with, Henry Cavendish had 272,800 pounds from
these sources, and he had several thousand pounds in securities in
his own name. The above information is from the ledgers of the
Hank of England Archive: South Sea Annuities I 77f>— 1 7MA, vol. 154.
p. 65; Bank Stock. 1783-1798, No. 59, p. 389, and 1798-1815, No. 64,
p. 439; Reduced 3% Annuities. .Supplement Ledger, 1781-1785, p.
10614, and 1785-1793. pp. 1505. 2242. and 1793-1801, pp. 1727.
1801, and 1803-1807. p. 1937. and 1807-1817, p. 6001; Consolidated
37r Annuities. 1782-1788. pp. 3449-50, 3854, 3927, and 1788-1792,
pp. 8000. 8619, and 1792-1798. pp. 8000, 8730, and 1799-1804. pp.
8001. 9012. and 1804-1812. p. 8001; South Sea Old Annuities, vol.
79, 1776-1786, p. 90. and vol. 90, 1794-1815, p. 648.

;4 Ceorgc Wilson. The Life of the Honourable Henry Cavendish
(London. 1851 ). 175-76.

"There is correspondence from his bankers in Devon. Coll.,
86/comp 3.

"'■Cavendish's undated draft of a letter to Alexander Dalrymple's
administrator: Devon. Coll., L/34/64.

"In literal translation, Biot's epigram is wordier: Cavendish was
"the richest of all the learned and probably also the most learned of
all the rich." J. B. Biot. "Cavendish (Henri)," Hiografihie Universelle
vol. 7 (Paris. 1813). 272-73. on 273. The alleged uncle who left his
fortune to Henry Cavendish in 1773 was repeated in biographical
dictionaries including the must important of them all for scientists:
"Cavendish. Henry," in J. C. Poggendorff, Biographisch-Literarisches
Handwb'rterbuch surGeschichte tier exacten W'issensrhaflen, vol. 1 (Leipzig.
1863), 406. In a variant explanation, this one closer to the mark,
Thomas Thomson said that besides Cavendish's father, an aunt left
him a great deal of money after his father's death: History of Chemistry.
vol. 1 (London, 1830): 336-49, on 336. 'The different accounts are
discussed by Wilson, who regarded as unimportant the source of
Cavendish's wealth but not the timing, which he placed no later than
1783: Cavendish, 158-60.

Copy rig hi

Last Years

355

the mistaken assumptions about his late friend's
finances. For his eloge of Cavendish, Georges
Cuvier went direetly to Blagden, but he also took
details from Biot's biography, whieh was filled with
errors. Blagden let Cuvier know this and, in
particular, that he had the origin of Cavendish's
fortune wrong. Blagden believed it was Cavendish's
father, and he was right. 7K

Henry Cavendish once again followed his
father's course, investing in gilt-edged securities
and not touching them. Shortly before his father's
death, when he was establishing an independent
life, Cavendish sold a small part of his securities,
8,500 pounds worth, but that was the exception.
From the ledgers of the Bank of England, we see
that Henry Cavendish's account increased steadily
and by modest increments. During the Napoleonic-
Wars, the government offered a higher return on
loans and very substantial bonuses as a percentage
of capital on top of the half-yearly dividends, and
so in these latter years Cavendish's account rose
much faster than before. Pitt's great experiment
with an income tax in 1800 excluded dividends. If
the figure of 80,000 pounds in the story about
Cavendish and his banker is at all close, the time
would have been the Napoleonic, when money
poured in, and it would have been easy to lose
track; toward the end Cavendish's securities earned
him, in effect, ten percent on his investment,
which came to around 80,000 pounds per year, the
figure quoted in the anecdote of Cavendish and his
banker. 7 '' When Cavendish died in 1810 most of his
stocks were selling below par, which was usual. On
paper their value was well over a million pounds;
their discounted value was about 821,000 pounds
for stocks in his own name and about 18,000
pounds for stocks in trust. Cavendish owned some
of every kind of security, but the bulk of his
investment was in only two, consols and reduced
three percent annuities. He still owned the 48,000
pounds in mortgages given to his father by
Elizabeth Cavendish. And his banker had about
11,000 pounds cash in hand.* 0 Henry Cavendish's
fortune compared favorably with some large
fortunes in the late eighteenth century: Lady Bute's
800,000 pounds, Lord Bath's 1,200,000 pounds, and
Sir Samuel Fludyer's 900,000 pounds.* 1

As Biot said, Cavendish was the richest of
the wise, and insofar as his investments were
concerned, he was at least one of the wiser of the

rich; over the long run, during the years in which
he amassed his fortune, he could hardly have done-
better than to buy into Bank of England stocks,
especially since he was a man who had other things
to do with his days than to spend them in his
counting house.

End of Life

The Devonshire estate papers contain
several letters between Henry Cavendish and his
brother, Frederick, saved perhaps because they
mention their banker along with a couple of small
sums. The letters, falling in 1806 to 1810, give us a
glimpse into the brothers' relationship near the end
of their lives.

The brain damage Frederick suffered from
an accident at age twenty-one did not otherwise
affect his health. In their letters the brothers
showed equal and largely unnecessary concern for
one another's health. Henry had heard that
Frederick was ill, and Frederick reassured him that
he had never felt better other than for the gout that
cramped his handwriting. He lived still in Hert-
fordshire, just across the border from Bedfordshire,
in Market Street, a quiet village near the
Benedictine Monastery of St. Albans. 8 - He liked to
walk, which he did in old age with his carriage
ordered to follow behind him. He spent his time
visiting in the neighborhood, where he was
regarded as a harmless eccentric and a soft touch.
He gave to all needy comers, the poor, the out of
luck, the church. People came to him from con-
siderable distances, since they had reason to expect
that they would not go away empty handed.
Bookish, whiggish, intelligent, unfashionable, in
several respects Frederick resembled his brother.

78 Blagden's correspondent Madame I). Gamier was acquainted
with Cuvier's wife. On 30 April 1H1 1 Gamier communicated Cuvier's
thanks to Blagden, and on 20 April 1 S 1 2 Blagden wrote back after
seeing Cuvier's eloge. Blagden Letters. Royal Society, G.ll and
G.lla. (icorges Cuvier, "Henry Cavendish." translated by I). S.
Faber, in Great Chemists, ed. K. Fabcr (New York: lnterscience
Publishers, 1%1), 229-38.

"Clapham, Rank of England 2:39-40, 46.

""Mess. Snow & Co.. "Valuation of Property in the Funds," 24
Feb. 1810. Devon. Coll., L/l 14/74. Cavendish's mortgages were from
the duke of Devonshire and Knight Mitchell, and the trust was
under the names of Lord Hardwicke, Lord George Cavendish, and
Lord Frederick Cavendish.

*' L B. Namicr, Structure of Politics at the Accession of George 111. 2d
ed. (London: Macmillan, 1957), 164.

82 Hcrbert W. Tompkins, Highways and Rvways in Hertfordshire
(London: Macmillan. 1902). 113-14. 139.

356

He had a huge library, though of classics and
literature and not of science. He had the re-
markable memory of the Cavendishes; his he
devoted to poetry, which he could recite with such
accuracy that he was called a "living edition." He-
was fond of modern poets, such as Thomson,
Akcnside, Ciray, and Mason; it was thought that his
selection of favorites was influenced by their
politics. For Frederick was at one with his family, a
staunch whig of the old school. Fxtremely proud of
his family, he was given to quoting the epitaph of
the first duke of Devonshire, friend of good princes
and enemy of tyrants. The outward appearances of
these bachelor brothers were fixed in their youth;
with his bag wig, cocked hat, and deep ruffles,
Frederick in his later years was a quaint relic, like
Henry with his much commented-on way of
dressing. In his later years Frederick was not as
well as he let on, but his way of life was
unaffected. s; He continued his charity to one and
all. One of his last letters to his brother is about a
young married man who was just getting started
and needed 150 pounds to pay off his upholsterer's
bill. Frederick asked Henry for this amount, since
he did not have it. Henry obliged his brother, who
was "confident /it/ will do a great deal of good."* 4
I lenry received a thank-you letter from the young
man. xs (Typical of Henry was his response about
this time to a man with fourteen children and as
many literary projects, asking Cavendish to give
him 2000 pounds a year for the next five years
while he completed them; Henry wrote him that
he "must decline. ) Frederick's income came
from two sources, annuities in his own name, and
funds in trust, in about equal amounts; he had a
comfortable income, but he exceeded it and had to
ask I lenry for money. 87 He needed help with his
property taxes, which were (then as now) baffling.
Henry was sympathetic: "The printed forms sent
both by the comissioners of Income & assessed
taxes are intricate cv not clearly expressed. " xs
Frederick was mindful of his brother's interests:
"As I believe you attend a good deal to the
observation of the barometer," he sent Henry a
careful account of the reading by his barometer
that morning. I le said he had read in the paper that
Herschel predicted a wet end-of-summer, and
Henry, w ho had read this in the paper too, told his
brother that Herschel could have said no such
thing since he had "too much sense to make

Cavendish

predictions of the weather." 81 ' Such was the last
existing correspondence between the brothers.
Frederick was two years younger than Henry, and
he outlived him by two years.

Life span in this branch of the Cavendish's
was remarkably constant. In this respect, as in so
many others, Henry (like Frederick) was like his
father: they lived to seventy-nine. Up to the end,
Henry Cavendish was vigorous, physically and
mentally.'"' Blagden, though a physician, was not
Cavendish's physician, for among perhaps other
reasons he had stopped practicing. Cavendish's
choice was his good friend, John Hunter. The first
we hear of him as Cavendish's physician was in
1792, when Cavendish was sixty. Blagden went to
Clapham Common only to be told, to his surprise,
that Cavendish was ill. Blagden responded with
sympathy (and perhaps hurt): "If you had chosen
that I should wait upon you, I cannot doubt but
you would have sent to me."'" That same day he
learned that Cavendish was being seen by Dr.
Hunter, and he wrote again to Cavendish saying
that he "could not do better" and asked only if he

s ""Mcmoirs of the Late Frederick Cavendish, Esq," Gentleman's
Magazine %Z(\mZ): 289-91.

"Frederick Cavendish to Henry Cavendish, 5 and 12 Feb. 1810.
Devon. Coll., 86/comp. I.

"'George Marriott to /Henry Cavendish/, 15 Feb. 1810. Devon.
Coll., 86/comp. 2.

"•John Sinclair to I lenr\ Cavendish. I July 1809; Henry
Cavendish to John Sinclair, n.d.. draft. Devon. Coll.. 86/comp. 2.

"'Frederick Cavendish to Henry Cavendish. 0 Feb. 1810,
Devon. Coll., 86/ comp. 1. At the beginning of 1X10 Frederick's
assets were his estate in Market Street, where he lived, and his
funds, which were invested primarily in three-percent reduced Bank
of England annuities, old South Sea annuities, and new South Sea
annuities, totaling a little ov er 47.000 pounds. That year I lenry died,
leav ing Frederick his farms and his Clapham freehold estate, which
added about 3500 pounds to Frederick's income, otherwise derived
solely from his funds. Devon. Coll., I./l 14/74.

""Frederick Cavendish to Henry Cavendish, 28 Oct. 1806;
Henry Cavendish to Frederick Cavendish, n.d.. draft, Devon. Coll..
86/comp. 1.

"Frederick Cavendish to Henry Cavendish, 10 Sep. and 18
Dec. 1809; 1 lenry to Frederick, n.d., draft, Devon. Coll.. 86/comp. I.

'"'There is an unexplained entry in the inventory of papers
Henry Cavendish made sometime after his father's death. Labeled
"Mine." i.e.. Henry Cavendish's papers and not his father's or other
family papers, the entry reads: "Receipts from hospitals." It is
unlikely that Henry Cavendish would have received treatment at a
hospital. File receipts may he for donations. Charles Cavendish's will
left 1000 pounds to charity, to be dispersed at the discretion of his
executor, who was I lenry Cavendish. Hospitals would have been a
convenient choice for Henry and one consistent with his scientific
outlook, and as executor he would have kept receipts. Henry
Cavendish, "List of Papers Classed," Cavendish Mss, Misc. Charles
Cavendish's will, Devon. Coll., L/69/12.

"Charles Blagden to Henry Cavendish. 12 Mar. 1792. draft.
Blagden Letterbook, Royal Society 7:624.

Copyrighted material

Last Years

357

could visit shim "as a friend."'* 2 Cavendish invited
Blagden, who told Banks the next day that he was
"engaged to be with Mr Cavendish (who is much
disposed) at Clapham.'"" In his discomfort, whatev er
it was, Cavendish was with two friends, Blagden
and I lunter.

Since there was a famous contemporary
surgeon and anatomist named John Hunter, we
need to point out that Cavendish's doctor was not
that John Hunter. He is not well known today but
at the time he was highly regarded for his scientific
as well as medical skills. He was proposed for
membership in the Royal Society in 1785, and his
certificate was signed by twenty-five Fellows of
the Royal Society,'' 4 which was the same number
Captain Cook received ten years before in an
extraordinary expression of support. Cavendish was
one of the signers, along with all of Cavendish's
good friends, Dalrymple, Aubert, Heberden,
Blagden, Nairne, Smeaton, Maskelyne, and others
including the other John Hunter. Hunter was then
a physician to the army who was, his certificate
read, "well versed in various branches of natural
knowledge."

At the time of his election to the Royal
Society Hunter was thirty-one. He was a graduate
of the University of Edinburgh, and his writings on
medicine show that he followed the teachings of
William Cullen. His dissertation of 1775 was
remarkable for its subject, anthropology, but just as
he has been eclipsed by his namesake, his
dissertation has been eclipsed by a more famous
work on the subject appearing in the same year by
J. F. Blumenbach. 95

Hunter regarded humans as a species and
the differences among them as varieties, just as
with plants, butterflies, and shell creatures, which
natural history took more interest in than in man.
He looked into the natural causes of differences of
color, stature, parts, and minds of men. One of the
main causes of differences was "heat," which is
where his path crossed Cavendish's.'"> Before
I lunter went to Jamaica in 1780 to superintend the
military hospitals, Cavendish suggested that he
observe the heat of springs and wells while he was
there. His paper on the subject appearing in the
Philosophical Transactions for 1788 referred not only
to Cavendish's stimulus but also to mean
temperatures taken by Lord Charles Cavendish
and Heberden (who had helped secure his military

appointment). Hunter gave a full account of the
purpose of the observations, which was
Cavendish's hypothesis: the heat of the earth now
comes solely from the sun, not the earth's interior,
and so precise measurements of the temperature
deep enough inside the earth to remain constant
through the seasons should provide the mean
temperature of any climate; in this way a few
observations would teach as much as "meteorological
observations of several years.'"' 7 Hunter included
these observations in his main publication,
Observations on the Diseases of the Army in Jamaica?*
Hunter's other publications were on medical topics
in medical journals, and the judgment on his work
is that it did not live up to its early promise. He
died at the age of fifty-four, in 1809, the year
before his famous patient Cavendish died, and he
had not published any new work in over ten
years." In his will, Cavendish left a legacy for
Hunter along with his other scientific friends,
Blagden and Dalrymple.

The next illness of Cavendish we learn
about again from Blagden. Cavendish was a faithful
attender of Banks's open houses, so that when
Cavendish was absent one Sunday in 1804,
Blagden made note of it. IIMI A few days later
Blagden was informed that Cavendish was ill. 101

"-Charles linden to Henry Cavendish, 12 Mar. 1792. draft.
Blagden Letterbook, Royal Society, 7:625.

,,; Charles Blagden to Joseph Banks. 13 Mar. 1792. draft. Blagden
Letterbook, Royal Society, 7:626.

,,J 12Jan. 1786, Royal Society, Certificates, 5.

"I I u titer's dissertation is rightly eclipsed by the other, though it
has an interest of its own. Blumcnbach's De generis hutnani varietate
nativa was translated by T. Bendyshe and published together with a
translation of Hunter's Disputatio inauguralis quatdam fie Hominum
varietatibus, a harem causis exponent . . .(Edinburgh, 1775) in the
Anthropological treatises of Jokann Friedrich Blutnenbach . . . una' /he
Inaugural Dissertation of John Hunter, Ml). On the Varieties of Man
(London, 1865).

'"'Hunter, On the Varieties of Man, 365-68, 378.

"John Hunter, "Some Observations on the Heat of Wells and
Springs in the Island of Jamaica, and on the Temperature of the
Karth Below the Surface in Different Climates." PT 78 (1788):
53-65, on 53. 58, 65. Charles Blagden to William I-'arr, 21 Jan. 1788,
draft, Blagden Letterbook. Royal Society. 7:107.

'"Hunter included the paper from the Philosophical Transactions
as an appendix to the second edition of his Observations on the Diseases
of the Army in Jamaica (London, 17%). The first edition was in the
same year as the paper. 1 788.

"Lise Wilkinson. - The Other' John Hunter, M.D., F.R.S.
(1754-1809): His Contributions to the Medical Literature, and to the
Introduction of Animal Kxperimcnts into Infectious Disease
Research," Notes and Records of the Royal Society 36 ( 1 982 ): 227^» 1 , on
235-36.

""'12 Feb. 1804. Blagden Diary. Royal Society, 4:201.

1111 16 Feb. 1804. Blagden Diary. Royal Society. 4:back 202.

Cavendish

Cavendish was attended by Kverard Home, F.R.S.,
anatomist, and surgeon at St. George's. From
Home, Blagden learned that Cavendish had a
rupture, nothing more serious; he would need a
truss, that was all. Home was about the same age as
Hunter, and at the same time as Hunter he had
served with the army in Jamaica; the two were well
acquainted, both ac tive members of a medical club
founded in 1783, which met at Slaughter's Coffee
House. 102 In 1804, when Cavendish called on his
services. Home was a famous surgeon, having
succeeded the John Hunter as surgeon to St.
George's, and he was a prolific writer on surgical
and anatomical subjects. He was well known to
Cavendish at the Royal Society, where he
repeatedly was chosen to give the physiological
Groonian lectures." 1 '' As he had with his previous
physician, the "other" John Hunter, with Home
Cavendish had a scientific connection; in response
to a paper by Home, Cavendish did an optical
experiment on the cornea." 14 Unlike some of the
young scientists Cavendish was now around, such
as Davy and Hatchett, Home was "no great master
of the art of conversation," which may have struck
a chord with his silent patient." 15 Home would
attend Cavendish at the time of his death.

W hen Cav endish had his rupture, in 1804,
1 lome told Blagden that the disorder began with a
swelling of the legs: "as if old the first time,"
blagden wrote in his diary that day.""' Cavendish
was ill on 16 and 17 February, and Blagden went to
see him on the 18th. On the 18th Cavendish made
out his final will, though it seems that he did not
show it to Blagden. 107 Either Home or Blagden, or
both, had a true insight. Cavendish was seventy-
two, and he had an intimation of — perhaps a brush
with — death. But otherwise, outwardly, there was
no indication that Cavendish felt old.

With one exception, which we will get to.
Cavendish's formal scientific associations remained
of the same general nature to the end of his life. So
far as we know, he was not drawn to specialized
scientific clubs and societies, though these had
been in existence even before his father's time. At
the end of the seventeenth century, the Temple
Coffee House Botanic Club was formed, and Hans
Sloane and good number of eminent natural
historians belonged.""* In chemistry, a field close to
Cavendish's heart, there was the Chapter Coffee

House Society, formed in 1780, and characterized
at the time as a chemical society, though its
interests were probably broader than chemistry.
There was Bryan Higgin's short-lived Society for
Philosophical Experiments and Conversations, an
extension of Higgin's chemical lectures, which in
the mid 1790s taught Lavoisier's new chemical
nomenclature; Cavendish's friend Thomas Young
was one of the subscribers. At the very end of
Cavendish's life, a number of small, private
chemical societies were founded in and around
London: the London Chemical Society, announced
in 1807 by Friedrich Accum, a chemical teacher
and briefly Davy's assistant at the Royal
Institution; the Lambeth Chemical Society,
launched around 1809; and a group of young phy-
sicians and chemists with an interest in organic
chemistry who met as a dining club, the Society for
the Improvement of Animal Chemistry. 10 '' The
latter society had a close connection with the Royal
Society, as is made clear by the founding resolution
at a meeting of the council of the Royal Society in
April 1809. which designated the new society as an
"assistant society" that was in no sense in
competition with the original, 'lb underscore the
continuity with the old society, and to add prestige
to the new, at the same meeting the council
resolved "that Mr Cavendish be requested to allow
his name to be added to those of the members of

"'-'It was the Society for the Improvement of Medical and
Chirurgical Knowledge, which brought out a short-lived Transactions.
The leading spirit behind this society, or club, was t/ii' (other) John
Hunter. W ilkinson, "John Hunter," 234.

""William LeFanu, "Home. Kverard." DSB &A7H-7').

un \n 1795 Blagden sent Cavendish a paper by I lome, which we
assume was Home's account of what would have been in John
Hunter's Croonian Lecture if he had not died before he could give it.
Hunter believed that the cornea could adjust itself by its own
internal actions to focus the eye at different distances. Kverard
Home. "Some Facts Relative to the Late Mr. John Hunter's
Preparation for the Croonian Lecture," PT9A (1794): Z 1— 27. Blagden
then assisted Cavendish in his experiment to detect changes in the
convexity of the cornea accompanying changes in the focus, using a
divided object-glass micrometer. Kntries for H. II, and Hi Nov. 1795,
Blagden Diary, Royal Society, pp. 75 (back), 76, and 77 (back).

'""Benjamin Collins Brodie, Autobiography of the Late Sir
Benjamin C. Brodie, Hart.. 2d ed. (London. 1865), 92.

""•17 Feb. 1804, Blagden Diary. Royal Society. 4: back 202,
and 203.

'"'"Copy of the Will of Henry Cavendish Ksq," in the "Account
of the Executor of Henry. Cavendish Esq. as to Money in the
Kunds," Devon. Coll.. L/31/65.

'""David Klliston Allen, The Naturalist In Britain: A Social History
(London: Allen Lane. 1976), 10.

""Owen Averley, "The Social Chemists': English Chemical
Societies in the Eighteenth and Early Nineteenth Century," Ambix
33(1986): 99-12H, on 102. 107-9, 1 13.

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Last Years

this new society." 110 The meetings took the form of
dinners and conversation every three months held
alternately at the house of Cavendish's doctor,
Home, and at the house of his collaborator Hatchett.
Other members included their friends Davy, William
Thomas Brande (who would succeed Davy as
professor of chemistry at the Royal Institution), the
physician William Babington (one of the founders
of the Geological Society), and the physician
Benjamin Collins Brodie (who was the outstanding
pupil of Home). 111 Later the Society turned into a
mere dinner club, but at the beginning it was given
to serious scientific discussion. If Cavendish came
to any of the few meetings held before his death,
he would have been an interested party to these
discussions and not a monument from the past; in
1806, at least, Cavendish was still doing experiments
in chemistry-, such as a long series on platina," 2 and
we know that he came around to the Royal
Institution to observe Davy's experiments. In 1809,
the year of its founding, the Society sponsored two
papers printed in the Philosophical Transactions, one
by Home and one by Brande, both electrochemical.
Home's paper continued the discussion of the
electric eel or torpedo, Cavendish's subject; it is
revealing of the changed state of science that
Cavendish heard Home describe the torpedo as a
"Voltaic battery" instead of Cavendish's battery of
Leyden jars. The torpedo was now a problem of
chemistry rather than of electricity 1 u Cavendish's
membership in the society specializing in animal
chemistry was unique; as he did not join the large,
public specialized societies that began to appear at
this time, such as the Linnaean Society in 1788,
the Mineralogical Society in 1799, and the
Geological Society in 1807. His age might explain
it, but he was vigorous, and the suggestion was
even made that he add to his social obligations in
science: in 1805 Banks proposed to enlarge the
Board of Longitude and to include Cavendish. 114
The fuller explanation is, we think, that the great
national societies, which would eventually include
the Chemical Society of London in 1841, belong to
a different era of science than Cavendish's. They
emerged with the professional identity of the
scientific expert; Cavendish would no more have
been at home in a professional scientific society than
he would have been in one of the Inns of Court.

To the end Cavendish was fully active in the
work of the Royal Society, as visitor to the Royal

359

Observatory, as member of the committee of papers,
and so on. His last attendance at a council meeting
was on 21 December 1809. He missed only one
meeting, that of 15 Febniary 1810. When he died on
24 February 1810, he still had work for the Society in
progress, which brought him back to his starting
point. He had agreed to superintend the construction
of an apparatus for measuring the temperature in the
depths of the sea. His father had recommended this
use for the thermometer he invented over fifty years
before, and Henry Cavendish had made apparatus
for this purpose. He did not have time to do the
experiment once more.' 15

When (ieorge Wilson came to write about the end
of Cavendish's life, he found, to his regret, an ap-
parent absence of any spirituality in his subject. 116
The Cavendish family had extensive connections
with the Church: the duke of Devonshire had the
second largest patronage empire, holding twenty-
nine and a half livings, 117 but this had to do with
temporal power, not spiritual inclinations. Lord
Charles Cavendish might have had an interest in
religion; at least he was willing to give to an
endowment for the Fairchild Sermon, which was
overseen by the Royal Society. 1 w But if there was
any religion in the family, there was no fervor. That
absence would not have shocked Cavendish's doc-
tor, Home, as it did Wilson; Home was a materialist
who regarded the mind as an arrangement of
matter and denied any difference between man

' "'27 Apr. 1809, Royal Society. Minutes of Council. 7:527-31.
1 1 1 . 1 utobiopaphy of the Late Sir Benjamin Brodie, 88-92 .
"-'In January 1806, e.g.. on platina: "White Book." Cavendish
Mss. p. 68.

"'Evcrard Home, "Hints on the Subject of Animal Secretions,"
/T99(1809): 385-91, on 386.

"«23 Feb. 1805, Blagden Diary. Royal Society, 4:313.

"The clerk of the Royal Society, Cilpin. died right after
Cavendish; Gilpin was going to oversee the actual construction of the
apparatus. Banks wrote to the person it was intended for that
Cavendish's "unexpected" death and Gilpin's death prevented him
from procuring it. Joseph Banks to William Scoresby, Jun.. 8 Sep.
1810, copy. Whitby Literary c< Philosophical Society

'"■Wilson, Cavendish. 180-82.

"■John Cannon, Aristocratic Century: The Peerage of Eighteenth-
Century /•>#/W/(Cambridgc: Cambridge University Press. 1984). 64.

,l8 Lord Charles Cavendish was one of several Fellows of the
Royal Society who subscribed to increase the fund to pay a lecturer
to preach on Whitson at a certain church on the theme "The
Wonderful Works of God" or the "Certainty of the Resurrection of
the Dead." From 1746 the president and council of the Royal
Society chose the lecturer for this Fairchild Sermon. Ilcnry Lyons,
The Royal .Society, 1660-1040: A History of Its Administration under Its
Charters -(New York: Greenwood, 1968), 175-76.

360

Cavendish

and animal other than in the arrangement of mat-
ter. Many other eighteenth-century scientists had a
similar outlook; Martin Folkes, for example, when
presiding over the Royal Society scoffed at the
mention of anything religious." 9 Cavendish's think-
ing belonged to the rational, secular current of
thought of his time, which together with his
extreme privacy guaranteed that his religiosity, if
he had any, would not be evident to strangers or to
his biographers.

The several accounts of Cavendish's last
days vary but agree in this particular: Cavendish
was fully alert and resigned to the imminent end.
The account most at variance with the others was
given by I lome to John Barrow, who published it
long after the event. It is also the most likely. When
one of Cavendish's servants came to Home's house
to say that Cavendish was dying. Home went
directly to Clapham Common, finding Cavendish
"rather surprised" to see him there. His servant
should not have bothered Home, Cavendish said,
since he was dying, and there was no point in
prolonging the misery. Home stayed all night at
Cav endish's bedside. Through it all Cavendish was
calm, and shortly after dawn he died.' 2 "

be that account as it may. Home was
certainly there, we know from an entry in
Blagden's diary from the time. In fact, Home and
1 leberden were both there, as we know from
Home's account to Blagden and from Lord George
Cavendish, who as Cavendish's executor paid their
fees. 1 - 1 This Heberden was William Heberden, son
of Charles and Henry Cavendish's old friend, who
had died in 1801. The younger Heberden was as
distinguished as his father, at the time physician in
ordinary to the king and the queen. Home gave
Blagden an "affecting account" of Cavendish's
death the prev ious day. There was a "shortness of
questionings," Home said; Cavendish "seemed to
have nothing to say, nor to think of any one with
request." He told Home "it is all over, with
unusual cheerfulness, & at parting wished Home-
good by with uncommon mildness." Cavendish
ordered that his main heir. Lord Ceorge
Cavendish, "be sent for as soon as the breath was
out of his body, but not before." 12 - Home, who had
treated Cav endish's rupture six years earlier, as we
have seen, told Blagden that that the rupture had
had nothing to do with Cavendish's death, even
though he evidently had refused to wear a truss.

Cav endish had an "inflammation of the colon," which
for the past year had caused diarrhea but which in
the end obstructed the passage of food. 12 ' On the day
Cavendish died, Blagden heard about it at Banks's
house. Banks lamented the loss to science, but that
was all, "felt nothing." Blagden, by contrast, was
moved, noting in his diary that he "continued all day
to feel the effect of this event on my spirits." He also
noted that it was a cloudy, threatening day, as if a
mirror to his spirits. 124 Two weeks later Blagden
watched from his window the "funeral procession of
my late friend . . . with much emotion." 125

We now pass to another, all-too-human emotion.
Cavendish's fortune was on everyone's mind,
including Home's. The morning Cavendish died,
I lome got a servant to give him the keys, and he
prowled through the house opening drawers,
trunks, and cupboards looking for treasures, which
he found and noted. 12 ' 1 In a few days word was out
that no will had been found. Blagden had seen the
will but not "since the time I was intimate with
him," twenty-one years before, in 1 7S9. Blagden
knew he had been in the will then and thought,
correctly, that Cavendish had probably changed it
since then. 127 The scientific men speculated and
questioned Blagden, who had known Cavendish
best. Blagden told them that Cav endish got 40,000
pounds a year. Cavendish was known to be not a
"person who gave the 40,000 pounds to hospitals,"
and since Cavendish did not spend more than
5.000 pounds a year (so Blagden told them), he had
to hav e left a fortune. 128

"''Keith Thomas. Man anil the Natural World: .1 History of the
Modern Sensibility (New York: Pantheon. 1983). 124.

'-"John Barrow. Sketches of the Royal Society anil Royal Society Club
(London, 1X49), 153-54.

'-'Heberden prescribed neutral salts (as it happened, the
subject of Cavendish's first chemical experiments), which he could
not keep dow n. 25 Feb. 1810, Blagden Diary. Royal Society. 5:back
p. 426 and p. 427.Home's fee was 105 pounds. Hcberdcn's 21 pounds.
Lord George Cavendish, "Mr Cavendish's Executorship Agenda,"
Devon. Coll.

'-25 Feb. 1810, Blagden Diarv. Royal Society, 5:back p. 426 and
p. 427.

I23 4 Mar. 1810. Blagden Diary, Roval Society, 5:back p. 429 and
p. 430.

'-•'24 Feb. 1810, Blagden Diary. Royal Society. 5:p. 426 and back
p. 426.

'-' s 8 Mar. 1810, Blagden Diarv. Roval Society, 5:back p. 431 and
p. 432.

'-'''Barrow, Sketches, 154—55.

'"1 Mar. 1810, Blaj;den Diary, Royal Society, 5:back p. 428.
IJ "1 and 2 Mar. 181(1. Blagden Diary, Royal Society, 5:back p.
428 and p. 42').

Copyiighled maieiial

Last Years

361

In time the will was found, and Blagden
was informed that he was left 15,000 pounds.
Dalrymple and Hunter were each left 5,000
pounds, though both of them had died since 1804.
These were trifling sums, relatively speaking.
Cavendish's wealth came from the family, and now
it went back to its source. His landed property was
entailed to his brother, Frederick; his personal
property was left to Lord George (Augustus Henry)
Cavendish, his executor. As for the funds — over
800,000 pounds — one sixth went to Frederick
Ponsonby, the third earl of Bcssborough 1 and Five
sixths to Lord George Cavendish and his family;
the latter was portioned into two sixths for Lord
George and one sixth each for Lord George's three
sons, William and, still minors, the namesakes of
our branch of the family, Henry and Charles. Both
Lord Charles and Henry Cavendish had a history
of dealing with Lord George over property, 130 and
I lenry had decided on Lord George as his principal
heir long before he died. Lord George had married
sensibly and so was rich, even by Cavendish
standards; Henry Cavendish's legacy had nothing
to do with need but only with loyalty, fairness, and
duty. The dukedom would eventually revert to
Lord George's descendants, an eventuality Henry
Cavendish might have considered. The present
(fifth) duke of Devonshire, brother of Lord George,
was "quite convinced" that Cavendish would leave
him nothing, and he was right. 1,1 Resigned to
nothing, the duke was delighted to learn that
Cavendish had left his money to the family,
specifically to the earl of Bessborough. The duke
however was "disgusted to see the disposal of so
vast a property in a few lines, as if to save trouble . .

"132 We have seen many wills from the time and
none briefer (or clearer) than 1 lenry Cavendish's.

By the way he disposed of his wealth.
Cavendish gives us a view of how he saw his family
relationships. Apart from his brother, he had
outlived his own generation of Cavendishes. Of the
next generation, there were Five prospective male
heirs, only two of whom Henry named in his will,
Lord George Cavendish and Frederick, earl of
Bessborough (son of Lady Carolina Cavendish,
daughter of the third duke of Devonshire). It was
said that Cavendish enriched Bessborough because
he was pleased by his conversation at the Royal
Society Club. 133 That reason seems unlikely and is
certainly insufficient, since not only was Cavendish

not a conversationalist, but Bessborough was not a
member of the Royal Society nor of its club. ( That
is not to deny that Cavendish was closely associated
with the Bessboroughs. Cavendish and Bessborough 's
father, the second earl, saw one another constantly,
as both were active trustees and members of the
standing committee of the British Museum. But
this Bessborough, whose house at Roehampton was
filled with valuable Italian and Flemish paintings,
gave the Museum objects of art, not of science. 134
Frederick, the third earl and Cavendish's heir, met
regularly with Cavendish at the Museum, where
they were both managers). The more likely princi-
pal reason for Cavendish's bequest is family connec-
tions of the usual kind. Bessborough 's father was
secretary to the duke of Devonshire when he was
lord lieutenant of Ireland. This duke borrowed money
from Lord Charles Cavendish for the portion of his
sister Flizabeth upon her marriage to the second
earl of Bessborough. 1 55 The third earl of Bessborough
was married to Lady Henrietta-Frances Spencer,
sister of Georgiana, duchess of Devonshire and
friend of Henry Cavendish. Henry Cavendish was in-
volved with Bessborough over property. 136 Cavendish
probably liked Bessborough too, but friendship
would have been only one of the considerations.
With his principal heir. Lord George, Cavendish
seems to have had only a formal relationship,
meeting with him once a year for a half hour. 137 The

|M This was Frederick Ponsonby, third curl of Bessborough, and
second cousin to I lenry Cavendish. I lis father was married to I lenry
Cavendish's first cousin Carolina Cavendish.

""For example: schedule of deeds delivered by Lord Charles
Cavendish to Lord George Cavendish in 1780: Devon Coll., comp. 3.

1,1 Letter from the fifth duke's second wife, Elizabeth Foster, to
Augustus Foster, 1 Mar. INK), in T/ie Two Duchesses. Georgiana Duchess
nl IMoushire. Elizabeth Duchess of Devonshire. Family Correspondence,
ed. V. Foster (London, 1898), 545.

'^Quotation from the "Journal" kept by the duchess of
Devonshire, in Dorothy Margaret Stuart, Dearest Hess: The Life and
limes of Lady Elizabeth Luster, Afterwards Duchess of Devonshire
(London: Methuen, 1955), 174.

'"This piece of information is from Cc-orgc Wilson, who also
said that Cavendish "was not, I believe." related to Bessborough.
Wilson missed rheir family connection, though it was close. Wilson.
Cavendish, 190.

"••Entry for 2 June 1775, "Diary & Occurrence-Book of the
British Museum, Ap. 2nd 1775 to April 1782 (Signed Dan.
Solandcr.") BL Add Mss 45875. p. 76.

'""Bond from His Oracc the Duke of Devonshire to the Rt.
Hon 1 ' 1 ' Lord Charles Cavendish," 22 Sep. 1745. Devon. Coll.,
L/44/12.

"' Henry Cavendish and the duke of Devonshire to the earl of
BessboroiiKh. lease for a year. I Nov. 1805: Devon. Coll.. L/55/22.
"'Wilson. Cavendish, 175.

Last Years

363

and it was elaborate and expensive. The pace of
the procession was appropriately funereal, nine
days to and from Derby. Everything had to be
rented for that period, the hearse and coach
ornamented with black ostrich feathers and drawn
by six horses, eight men on horses, and on and on.
There were five private carriages belonging to the
duke of Devonshire and to Henry Cavendish's
heirs, Lord George Cavendish, Lord Bessborough,
and Lord George's oldest son, William Cavendish.
The bill for nine days came to about 750 pounds. 14 ''
One of Lord George's minor expenses was
the inscription on Cavendish's tomb. He might have
followed the example of Archimedes, whose tomb,
at his request, was inscribed with a sphere inside a
cylinder, whose proportions he had determined.
Cavendish's tomb would then have had a sphere
and a circular plate of the same diameter, the
electrical charges of which Cavendish determined
were in the proportion of 1 to 1.57, to the wonder of
later scientists. 147 But nothing so scientifically
fitting was done. What went onto Cavendish's tomb
was traditional and otherwise fitting, composed, we
think, by Blagden for the family:

Henry Cavendish Esq. F.S.A. Son of the late Lord
Charles Cavendish, one of the old Council and a
Fellow of the Royal Society and an elected trustee
of the British Museum. Born the 10th of October
1731. Died February 24th 1810. 14 *

The scientific colleagues who gathered at
Banks's house in the weeks following Cavendish's
death had concerns other than his will, about which
nothing could be done. For one thing, there was
Cavendish's great library, which passed along with
all of his other personal possessions to Lord
George. Blagden knew that Cavendish wanted it
not to be dispersed but to be kept accessible, as it
had been in his lifetime. 14 '' There was no doubt
talk about Cavendish's instruments, for Davy was
soon to be given his pick of them, while others
went to the instrument-maker John Newman of
Regent Street, son of the maker of Cavendish's
wind measurer. 150 .

Of great importance to Cavendish's col-
leagues were his scientific papers, and with this
subject we come around to our starting point; for if
Cavendish's papers had not been preserved, we,
his biographers, would not have got far. From the
first days there was talk of an edition of
Cavendish's published works, but just what to do

about his unpublished papers was an open
question. 151 Blagden thought that these papers
would be found in a state unfit for publication.
Lord George wanted Blagden to look over the
papers anyway, and so on 6 April Blagden, Banks,
and evidently other interested colleagues met with
Lord George at Cavendish's house at Clapham
Common to inspect the manuscripts. After
spending about four hours on them they decided
that the papers were, for the most part, "only
mathematics." Blagden returned to Cavendish's
house, and for the next two weeks he was kept
busy with the papers, after which he reported to
Lord George:

We have now finished the search which your
Lordship desired us to make, in the hope of
finding, among the papers of the late Mr Henry
Cavendish, something which he had prepared &
thought fit for printing. Our search has in this
respect been fruitless; a result for which we are
sorry, though we must confess that it was not
unexpected to us; because we knew that Mr
Cavendish was always ready to publish whatever
he had made out to his full satisfaction. There are
some few small scraps, which are transcribed
nearly fair, as if he had thought of communicating
them to the R.S.: but as it is apparent that they
have been laid by, in that state, for a considerable
time, it is to be supposed that he afterwards
discovered some weakness or imperfection in
them, or that they had been anticipated in a
manner of which he was not aware when he
composed them; in short, that he had some good
reason for not giving them to the public. In truth.

*"Mt Swift's Bill for Expenses Arte the Funeral of Hen:
Cavendish Esq.," 29 Aug. 1810, Devon. Coll.. L/l 14/74.

'■"The inscription could have been globe and cylinder, exactly
like Archimedes', since Cavendish measured their relative capacities
too. For the circular plate and sphere. Cavendish did several
experimental determinations, obtaining a value between 1.50 and
1.57. The latter value he preferred, since he entered it in the paper
he intended for publication. William Thomson came across the value
1.57 in Cavendish's papers in 1849 and remarked: "a most valuable
mine of results. I find already that the capacity of a disc (circular) was
determined experimentally by Cavendish as 1/1.57 of that of a
sphere of same radius. Now we have capacity of disc = Zln n =
rt/1.571!" Quoted in The Eleelrieal Kesermhes of the Honourable Henry
Cavendish, ed. James Clerk Maxwell (Cambridge, 1879), xxxix. In
1832 Ccorgc (ireen had derived the modern theoretical value for the
ratio: 1/2 Jt, or 1.57. Cavendish. Sri. Tap. 1: 433.

I4 ""H. Cavendish Esq. Inscription for the Plate on the Coffin.
Died 24 Feb. 1810," Devon. Coll.

I«3 and 4 Mar. 1810. Blagden Diary. Royal Society, 5:429. back
p. 429, and p. 430.

'■"'Wilson, Cavendish, 475.

,5l This discussion of Cavendish's papers is taken from Russell
McCormmach, "Henry Cavendish on the Theory of Heat." his 79
(1988): 37-67, on 37-38.

J64

Cavendish

Mr Cavendish's fame stands so high already in the
scientific world, that no papers lint of the most
perfect kind could be expected to increase it,
whilst it might be lowered by anything of an
inferior nature. 152

Blagden and his colleagues firmly recommended
against including any of the unpublished papers in
the proposed edition of Cavendish's papers, but
they expected that dates and circumstances of his
discoveries might be found among them that
would be useful for the introduction. Since the
papers were in "great disorder," some qualified
person with time to spare would have to be found
to go through them. They could think of only one
person, the man whom Cavendish sometimes
employed, the clerk of the Royal Society, George
Gilpin, but they decided that he was probably too
ill to take on the task. They supposed that Lord
George might ask around. Three months after
Cavendish's death, Blagden and Banks, between
themselves, agreed to postpone plans for an edition
of ( !a\ endish's works.

Blagden, Banks, and the others recognized
the perils of trying to improve a reputation

posthumously, but they were mistaken about the
worth of Cavendish's papers. That could hardly
have been otherwise, since the papers contained
much that was original, and much more than the
work of a few hours or a few days was required to
appreciate this. Blagden was right in thinking that
Cavendish's fame was then so great that no
unfinished papers could increase it, but he was
wrong about the future. Today Cavendish is nearly
as well known for what he did not publish as for
what he did. One eminent scientist after another
has studied his manuscripts and has come away in
wonder at what he achieved with the instruments
and concepts available to him. To them it has
seemed as if Cavendish were not of his own
century, but of the next. 153

l52 Charles Blagden to "My Lord" /Lord George Cavendish/, n.d.,
draft. Blagden Collection. Royal Society. Misc. Matter — I nclassified.

l53 For example: one hundred years after Cavendish had done
his experiments on electrical capacity, in 1K74. Maxwell wrote to W.
Carnctt, his future biographer, that Cavendish's "measures of
capacity will give us some work at the Cavendish Laboratory, before
vve work up to the point where he left it." Quoted in Joseph
Larmor's preface to vol. 1 of the 1921 edition of Cavendish's Sci. Pap.

IN CONCLUSION

£avendish

Henry Cavendish was the outstanding mathematical
and experimental scientist in Britain between
Newton and Maxwell. The first part of this esti-
mate was often made soon after Cavendish died, as
we have pointed out. The second half we make
with hindsight.

But what of Cavendish the complete man? Is
that question a contradiction in terms? In the
introduction to a course in chemistry in 1X55, the
lecturer warned his students: "It may be fairly
asked, why bring such a character forward for
examination? ... Is it enough not to be a villain, a
debauchee, a murderer? Or rather is it not our duty
to be something that shall create for positive good on
our fellow-men? To this the answer must be made,
that the character of Cavendish is not introduced as
a subject of admiration, or for imitation, but rather
as a warning to all men who cultivate the intellect,
that they do not neglect the social portion of their
nature . . ."' This lecturer had read a book
published four years before, George Wilson's The
Life of the Honourable Henry Cavendish.

Wilsons Cavendish is a vivid portrait of
Victorian negations, of a man lacking in piety,
family, philanthropy, and poetry. What Wilson
made of this moral negativism cannot be improved
upon, a perfect portrait of its kind. Concerned with
the individual soul, Wilson looked deeply into his
subject with his probe, morality, and rendered a
judgment, which was pitiless. The anecdotes
testifying to Cavendish's cold eccentricity can be
looked at another way, however, as evidence of
withdrawal and a desperate dependence on
external regularity. They are good anecdotes, but
they do not of themselves offer us an understanding
of the complete man. This is perhaps to say the
obvious: Wilson's Life of Cavendish cannot satisfy
our age as it did his.

We have presented Cavendish's life from the
perspective of science; according to our under-
standing, a life of science in the eighteenth century

could be a complete life for one as gifted and
directed as Cavendish. Moreover, it could be a rich
life, not an impoverished one. We have brought
forward not what is absent in our subject but what
is there, and what is there, within our subject, is in
part drawn from what is there outside it. The
familial, political, and scientific mansions that
Cavendish inhabited provided him with the
choices by which he gave shape and meaning to his
life. We have written this biography primarily from
the perspective of the social world of our subject.

Yet if any one scientist of the past invites
our psychological wonder, surely he is Cavendish.
Lest our biography appear incomplete in this
respect, we here briefly discuss a psychological
perspective, that of personality.

Consider one of the standard personality
traits used in psychological questionnaires today,
openness. Cavendish, a man of profoundly secluded
habits, was an outspoken champion of openness, one
who placed the utmost value on public knowledge
and the ideas of others. 2 The Royal Society with its
profession of openness was a congenial second
home for him. Between societies, too, he stood for
openness: he urged that as policy the Royal Society
and the Royal institution should exchange
materials presented to them. Famous, after his
lifetime, for his reluctance to publish his work.
Cavendish had rather, to put it provocatively, a
fever to publish. When he held back from
publication, which he often did, he did so not from
a desire for secrecy. He saw the damage secrecy did
to his friends, Michel), Canton, and Knight. He
refused Michell's request that he keep a discovery
secret and instead persuaded Michel! to let him
announce it to the world. He persuaded the
government to lift the official cloak of secrecy on

'The introductory lecture to a course on chemistry at the
National Medical College by Lewis H. Steiner. Henry Cavendish and
the Discovery of the Chemical Composition of Water (New York, 1 855), 6.

^Robert R. McCrca and Paul T. Costa. Personality in Adulthood
(New York and London: Guilford Press, 1 990), 44.

366

Cavendish

Hatchett's experiments carried out under his
direction. When asked his opinion on the author of
a scientific pamphlet who wanted to remain
anonymous. Cavendish "answered at once c\
decisively that the only way to make it produce anv
useful effect was for the author to sign his name";
Cavendish's "opinion, so decisively against its
being anonymous," caused the author to change
his mind and sign his name to it. 5 When he took
over his father's farms — to give an example from
outside science — he told his steward that the
condition of his job was complete openness.
Openness is a significant trait of Cavendish.

Let us consider another standard trait,
neuroticism. There is ample evidence that Cav-
endish suffered from intense anxiety. His voice was
excited, feeble, and hesitating, and at meetings of
scientists, he could be heard to utter a "shrill
cry . . . as he shuffled quickly from room to room."
In reaction to the stress of the outside world, he
lived as a solitary, "secluded," as Blagden said.

The term most often used to describe
Cavendish's personality by persons who knew him
was "shyness." 4 His shyness was extreme, a
disposition which — like its opposite in another
person, total lack of shyness — was and is regarded
as anti-social. Extreme shyness does not preclude a
public life and it is compatible with good social
skills, but it does make that life uncomfortable, as
Cavendish certainly found it to be. His anxiety was
greatest when he was in the presence of strangers,
especially those of the opposite sex. He was
observed to be awkward, show embarrassment, fall
silent, and if he had a chance, run. He was also ob-
served to approach strangers, revealing a mix of
interest and avoidance that is typical of excessively
shy persons. 5 I'pon seeing Cavendish for the first
time, a visitor at Banks's house noticed that
Cavendish was listening attentively to what he was
saying: "When I caught his eye he retired in great
haste, but I soon found he was again listening near
me."'' Morbid shyness is correlated with obsessive-
compulsive behavior, the subject of many Cav-
endish anecdotes. Another way of looking at it is
that by intelligently ordering his life in science,
Cavendish escaped a common outcome of shyness,
a delayed and poor career. 7 Thomas Young observed
Cavendish's "painful preminence": 8 the pain and
the eminence were inseparable. In the complete-
absence of records for Cavendish's early life, we

can only mention common causes of shyness,
which might have been present in his case. Even if
parents are considerate, children can be bullied by
caretakers into fearful shyness, or if children are
kept in isolation, their earliest fears of strangers
may never leave them. 4 That is compatible with
the modern finding that the onset of intense, irra-
tional fears of strangers and scrutiny is adolescence,
followed by a lifelong disability. It would seem
likely in any case that Cavendish's shyness had a
hereditary component. The taciturnity of the
Cavendishes was legendary, and of all the traits
of personality, shyness has the strongest genetic-
basis. 1 " In prevalence, among mental disorders.

'Charles Blagden to Joseph Banks. 24 and 26 Oct. 1 784.
BM(NH), DTC3: 83-86.

♦For example: John Barrow spoke of Cavendish's "extreme
shyness," confirmed by "all his habits": Cavendish seemed "to
consider himself as a solitary being in the world, and to feel himself
unfit for society": Sketches of the Royal Society unci Howl Society Club
(London. 184<M. 144. Another example: Henry Brougham spoke of
Cavendish's "peculiarly shy habits" and his "morbid shyness": Lives
of Men of I Attccs ami Stance Who Flourished in the Time of George III, vol.
I (London. 1845). 446.

'-Jonathan M. Cheek and Stephen k. Bri^K s - "Shyness as a
Personality Trait." in Shyness and Embarrassment: Perspectives from
Social Psychohjry. ed. W. Ray Crozier (Cambridge: Cambridge
University Press. 1990), .11.S-.V7, on 316, 31V, 322. Carroll E. Izard
and Marion C. Hyson. "Shyness as a Discrete K motion." In Shyness:
Perspectives on Research and 'treatment, eds. W. 1 1. Jones. J. M. Cheek,
and S. K. Briggs (New York and London: Plenum Press, 1968),
147-60. on LSI, 153.

''George Wilson. The Life of the Honourable Henry Cavendish
(London, 18.S1 ), 168.

'Cheek and Briggs. "Shyness," 328-29.

"Thomas Young, "Life of Cavendish." reprinted in Henry
( lavendish. The Scientific Papers of the Honourable Henry Cavendish, vol. 1 ,
ed. E. Thorpe (Cambridge: Cambridge University Press, 1921),
43.S-47. on 44.S.

''.Arnold 1 1. Buss, "A 'Theory of Shyness." in Shyness: Perspectives
on Research and 'Treatment, 39-46, on I I IS. Buss thinks that fearful
shyness and self-conscious shyness are distinct: if so, both behaviors
were ev ident in Cavendish.

"'Cheek and Briggs. "Shyness." 329. Jerome Kagan. J. Steven
Rezniek, and Nanev Snidman, "Biological Bases of Childhood
Shy ness. Scencc 240 ( 1988): 167—71. Debate about personality traits
goes through cycles, and some social and experimental psychologists
deny them entirely. 'There would seem, however, to be little doubt
that certain enduring emotional aspects of personality such as
tearfulness, so conspicuous in Cavendish, agree with an
interpretation relying on traits. Psychologists who work with traits
have more than one model from which to choose. According to one
in common use, five traits are sufficient to describe empirically the
configuration of any personality. Another uses seven traits grouped
into four traits of "temperament" and three of "character."
Temperamental traits, according to the latter model, are moderately
heritable and unchanging from infancy to adulthood: those of
character are only weakly heritable and are largely learned and
continue to develop through life. As this biography goes to press, we
note the first confirmed demonstration of a "specific genetic locus
involved in neurotransmission and a normal personality trait." 'The
trait in question is one of temperament, "novelty seeking," on w hich
Cavendish would rank exceedingly low. ( Although Cavendish enters

Copyrighted malarial

/;/ Conclusion

367

social phobia comes only after alcoholism and
depression."

We have noted that Cavendish would be
seen to freeze in front of the door at Banks's Sun-
day open houses, unable to go inside until other
guests approached him from behind. Cavendish
was not only a man of extreme social phobia but at
the same time a man of considerable courage, for
courage is required of one to perform the most
ordinary motions in society if one is afflicted as he
was. It was because of his courage that he did
science instead of pursue a reclusive hobby, since
doing science implies coming into the world.

Depression is a disorder of mood commonly
found in extremely shy people; 12 from that
disorder, we may speculate, Cavendish suffered all
his life. Concerning its causes, there is a range of
medical opinion, but on its symptoms there is good
agreement: lowering of vital activity, loss of interest,
absence of sexual desire, emotional unrespon-
siveness, irritability, and anxiety, among others. 15
Cavendish showed most of these symptoms. After
an evening spent in Cavendish's company, Blagden
normally noted one word in his diary to sum up
Cavendish's behavior. "Secluded," his word for his
character sketch of Cavendish, is not a word found
in his diary, nor would preferred it have been
fitting, since Cavendish was in Blagden's company.
The words Blagden used in his diary did, however,
suggest a desire for seclusion. They were harsh
words: melancholy, forbidding, dry, sulky. Occasion-
ally, and far less often, he used words of relief: civil,
civiler, and pleasant to talk with. Odd: peculiar,
eccentric, that which stands alone, solitary, singular.
Dry: showing no emotion, uncommunicative, cold,
distant. Sulky, obdurately out of humor, aloof, pas-
sive and silent in fending off approaches. "Dry"
and "sulky" are the words Blagden used most
often, and although he occasionally applied them
to Joseph Banks and other companions, he applied
them consistently only to Cavendish.

After a social gathering, Blagden wrote in
his diary, "talk about Mr Cavendish, & explanation
of character," 14 but he did not record what that expla-
nation was. On another occasion, after Cavendish
had left his party at the Monday Club, Blagden and
Aubert talked about Cavendish and agreed that he
had "no affections, but always meant well." 15 In a
moment of truth, Blagden confided in his diary:
"made nothing of C cannot understand him." 16 In

one respect biographers have it easier than do the
friends of the subject, since they do not have to
adapt to the living reality. But they have it harder,
too, in that they must come to an understanding of
their subject, however ambiguous and limited the
evidence. In the case of Cavendish, we, his biog-
raphers, must try to understand a man who could
be characterized by his friends as a man without
affections. Depression is commonly described as an
inability to feel affections; although they would
seem to have more reason to, depressed people cry
less than others, for the affect is suppressed. 17

In response to a correspondence begun by
Priestley, Cavendish said that he would send an
account of his experiments in the future, "but 1 am
so far from possessing any of your activity that I am
afraid I shall not make any very soon." 18 Compared
to Priestley, any person might feel inactive, but for
Cavendish inactivity was self-characterizing. For
six months Priestley's second letter went unanswered
by Cavendish, who apologized:

the standard histories of science as a "discoverer" of new truths ot
nature, he did not seek novelty as psychologists understand the
term; there is no contradiction here, as is clarified in Thomas S.
Kuhn's Structure of Scientific Revolutions.) The stories about
Cavendish's strange behavior all relate to heritable traits of
temperament; his life in science relates as well to the more plastic-
traits of character. We would not be surprised if future biographers of
Cavendish were to give even greater attention than we have to his
familial background. The rapidly expanding understanding of
personality on a fundamental scientific level promises useful insights
in this regard. C. Robert Cloninger, " Temperament and Personality."
Current Biology 4 (1994): 266-73. C. Robert Cloninger. Rolf
Adolfsson, and Nenad M. Svrakic, "Mapping Cencs for Human
Personality," Nature Genetics 12 (1996): 3-4. Richard P. Kbstein ct al.,
"Dopamine 1)4 Receptor (D4DR) Exon III Polymorphism
Associated with the Human Personality Trait of Novelty Seeking."
ibid., pp. 78-80. Jonathan Benjamin et al.. "Population and Tamilial
Association between the D4 Dopamine Receptor Cenc and
Measures of Novelty Seeking," ibid., pp. 81-84.

"1'rom a summary of a symposium on social phobia held on 18
Nov. 1993 in San Diego: "Practical Approaches of to the Treatment
of Social Phobia." Journal of Clinical Psychiatry 55 (1994): 367- 74.

'-'McCrae and Costa. Personality in Adulthood, 29.

"Max Hamilton. "Symptoms and Assessment of Depression,"
in Handbook of Affective Disorders, ed. E. S. Paykel (New York:
Guilford Press. 1982), 3-11.

I4 14 July 1795, Blagden Diary. Royal Society. 3:back p. 65.

>M5 Sep. 1794. Blagden Diary, Royal Society. 3:back p. 16.

I6 27 Aug. 1795, Blagden Diary, Royal Society, 3:67.

"Carol Zisowitz Stearns, "Sadness," in Handbook of Emotions.
eds. M. Lewis and J. M. Haviland (New York: Cuilford Press, 1993)
547-61, on 559.

'"Henry Cavendish to Joseph Priestley, n.d. /May or June 1784/,
draft. Cavendish Mss. New Correspondence; published in A Scientific
Autobiography of Joseph Priestley (1733-1804): Selected Scientific
Correspondence, cd. R.K. Schofield (Cambridge, Mass.: MIT Press,
1966), 232-33.

368

Cavendish

as I make not a tenth part of the exper that you do
e\ as my facility in writing falls short of yours in a
still greater proportion I am afraid you will think
me a had correspondent <N that the advantage lies
intirely on my side. .

During the dissensions of the Royal Society,
Blagden wrote to Banks that "Mr. Cavendish said
he had no other objection to taking the lead than
his unfitness for active exertion." 20 . Repeatedly
Cavendish abandoned promising researches, and
there were spells w hen he did no research at all but
only followed routine, the substitute for (inde-
pendable initiative.

Depression is fully compatible with scientific-
work of the highest order, even if it is seriously
interrupted; examples are Cavendish's contemporary
Joseph Louis Lagrange, and our Salvador Luria, who
has written movingly about it.-' 1 The earlier standard
image of the scholar as unequal to polite society,
contentious and melancholy, has counterparts in real
life throughout history.--' Newton was secluded and
morose, and so have been many other good scientists.

It is, of course, conceivable that Cavendish
suffered from an affective disorder of a far less
familiar kind, one which today might readily be
identified with this or that one-in-a thousand
syndrome. I lis habitual profound withdrawal led
one contemporary to characterize him as the "coldest
and most indifferent of mortals."--' 1 The last few-
years have seen the publication of a number of
neurological and psychological interpretations of
historical figures including scientists such as
Newton and Einstein; Cavendish, too, with his
singular drive to understand the universe, may well
one day invite such interpretation. Like everyone,
his neurological makeup together with his life
experiences imbued him w ith a select view of the
world; his, w e know, was inhabited by, among other
things, demons that he could subdue only by
imposing a vigilant orderliness on all phases of his
life. My following in his father's footsteps, he
brought his world together with that of science,
with its discoverable orderliness, the calming paths
of wandering stars, laid bare by nature, from w hich
demons are strictly excluded. How did he come to
make this choicer What did it mean to him?
Cavendish left no "inside narrative" of his life
telling us why science attracted him, nor would we
expect one from him, but other scientists have done
so. and their accounts may suggest questions that
could lead to a deeper understand of our subject. 221 '

We have deferred these observations on
Cavendish's personality to the end of this biography,
for we did not write it beginning with them. In the
Introduction, we discuss our direction and w hy we
take it. Mere we will make only one further point.
Other than for both being studious. Lord Charles
and Henry Cavendish do not seem to have had
similar personalities. Lord Charles was well
rounded, drawn to sports, races, and hunting. 23
Comfortable in society. Lord Charles was a man
who confidently assumed the chair at meetings. By-
contrast, ordinary company caused Henry acute

"Henry Cavendish to Joseph Priestley, 20 Dec. 1784. draft.
Cavendish Mss. New Correspondence; published in .1 Scientific
Autobiography of Joseph Priestley, 2.?<> — 10. on 240.

-'"Charles Bladen to Joseph Hanks. 5 Apr. I7K4. BM(NH)
DTC 3:20-21.

2, S. E. t.nria..l Slot Machine, n Broken Test Tube: An Autobiography
(New York: Harper & Row. 1984), 215-16.

--'Steven. Shapin. " A Scholar and a Gentleman': The
Problematic Identity of the Scientific Practitioner in Karlv Modern
England," Hist. Sci. 29 (1991 ): 279-327, on 290. 292.

-'-■Wilson. Cavendish, 17.?. A poignant, if ambiguous, entry in
Warden's diary reads: "Conversation about Monday Club. Mr.
C/avendish/ knew not what to do. Said some men without certain
feelings." 12 Nov. 1795. Blagden diary. RS. 3:76. If we are right about
Cav endish's interest in music, he had a means of expressing feeling
independently of companionship. The main task of music, as it was
understood in the eighteenth century, was not to imitate nature but to
imitate the feelings, and of all of the arts, music w as understood to be
the art that relatetl most directly to the feelings. Music and Aesthetics in
the Eighteenth Century and Early Nineteenth Centuries, ed. P. le I Iuray and
J. Day (Cambridge: Cambridge University Press. 1981). 3, 5.

z2h l ntil ten years ago, when Temple Grandin published an
autobiography. Emergence: Labeled Autistic, it was believed that an
inside narrative could not be w ritten by an autistic person. Regarding
herself as a "totally logical and scientific person" and her autism as a
disorder or affect and empathy, she recalls Cavendish in certain ways.
(We observe in Cavendish a number of autisticlikc traits: single-
mindedness, apparent inability to feel certain emotions, secluded-
ness, rigidities of behav ior, odd gait, harsh voice, strange v ocalizations,
panic attacks, self-acknowledged social unfitness.) Grandin does not
have feelings associated w ith personal relations, as a result of which
she misses those social signals that are the basis of humanity's
"magical communication." To deal w ith her "primary emotion," fear,
she has looked to "logic, science, and intellect": she has found the
language of science to be relatively free of implicit social
assumptions, inviting her to "make science her whole life." She-
regards her relativ ely mild, high-functioning form of autism not only
as a deprivation but also as a positive gift, endowing her with a
singlemindedness that enables her to excel. Holding the prevalent
view that there is a genetic component to autism, she believes that
the persistence of autistic traits has an evolutionary significance and
that persons with bits of them might be geniuses. Whatever the
neuropsychological basis of Cavendish's fears, he like Grandin
overcame them to achieve a productive, fulfilling life within seicnee.
Temple Grandin, Thinking in Pictures and Other Reports from My Life
sith Autism (New York: Doubleday, 199.S). 60. 172. 185-89. Oliver
Sacks, An Anthropologist on Mars (New York: Vintage, 1995), 165-65,
272-73, 277. 291-92.

-'Duke of Newcastle to the duke of Devonshire. 21 Nov. 1745.
Lord Harrington to the duke of Devonshire, 23 Dec. 1 746. Lord
Charles Cavendish to John Manners, IX June 1772, draft. Devon.
Coll.. Nos. \H2.M. 260.65. and L/l 14/32.

Copyrighted materia!

/// Conclusion

discomfort, and he would rather have been lashed
to the mast than outwardly to take charge. Yet in
their dedication to science and tireless attention to
the affairs of the Royal Society, they were very
much alike. Factors in addition to individual person-
ality were decisive in their choice of a common path.

Lord Charles and Henry Cavendish gave
themselves to science with the intensity that their
forebears, the early dukes of Devonshire, had
given themselves to politics. We have made the
case that in a certain sense their lives in science
began in Knglish dukedoms. We return to this
connection, to the qualification English. In
England the power of the nobility did not derive
from legal rights and royal favors but from
ownership of land. Land could be kept in the
family by marriage settlements, which in turn kept
the family intact with an identity that passed from
generation to generation.- 4 Lord Charles Cavendish
and after him I lenry had landed property, and
although the income from it was trifling in the
end — the great wealth of Charles and I lenry
Cavendish was the same as that of rich people in
the city, not land but stocks — the meaning of this
land was not trifling, since it derived from the
source of the family's place in society, its estate.
The landowner and the man of science had this in
common, an authority that resided in something
normally regarded as outside politics, and so out-
side time, as eternal.

The Knglish aristocracy escaped the fate of
their Continental counterparts, overthrown by
revolution, because they themselves had proved
ready to carry out revolution to protect their
property. The repeated rejections by the aristocracy
of attempts by the crown to increase its power
culminated in the Glorious Revolution at the end
of the seventeenth century, making the state
subservient to the landed interest.- 5 In eighteenth-
century England, a contented aristocracy acted
responsibly, ensuring its survival, and establishing,
as one commentator has put it, "the tradition of
public duty." 2f> That tradition contained within it, if
implicitly, the direction that Charles and Henry
Cavendish gave to their lives; in so doing they
extended the idea of public service.

Younger sons of the aristocracy, if not totally
dissolute, ordinarily went into the established
professions, especially politics and the military.

369

That brought them a supplementary income,
however small. Lord Charles Cavendish had a good
income from his family, which gave him some
choice, which he exercised by entering first politics
and then science. The professions in England had
greatly expanded in the fifty years before Lord
Charles Cavendish, but the new ones were largely
improvised and without formal training or standards
of entry, and science as not yet truly recognized as
an occupation. At around the time Lord Charles
Cavendish came of age, in the 1720s and 1730s, the
professions in Britain were harder to define than
before, and an experience of what we would call pro-
fessional solidarity was rare indeed, though esprit
de corps could be found here and there. 27 For the
Cavendishes, the ambiguous character of science
was fortunate, since if it had been regarded as a
profession equivalent to law or medicine, it would
have been foreclosed to them. Science instead was
open to interpretation, and like art or gaming or
amateur architecture or any kind of public service
bridging status and income, it could be embraced
by an aristocrat like Cavendish as a freely chosen
outlet for his energies. Cavendish's redirection did
not take social courage so much as intelligence and
imagination in thinking about the possibilities of his
social world.

In time Lord Charles Cavendish came to
recognize in science a complete sphere of action, a
world in becoming; in his son Henry's time, it was a
realized world, only one waiting to be generally
recognized. Henry Cavendish went beyond his
father's activity to the one that has come to be
valued highest in modern science, the advancement
of the knowledge of nature through published
research. (But we will have written this book in
vain if we have not made the point that in the
eighteenth-century, publication was only one and

- M H. J. Ilabukkuk. "Kngland," in Ehe European Nobility in the
Eighteenth Century, cd. A. Goodwin (London: Adam and Charles
Black, 195.?), 1-21, on I.

"M.L. Bush, The English Aristocracy: A Comparative .Synthesis
(Manchester: Manchester University Press. 1984), 12.

^Edward John B. D. S., Lord Montagu of Beaulieu. More Equal
Than Others: Ehe Changing Fortunes of the lirilish and European
Aristocracies (London: Michael Joseph, 1970), 156-57.

"Geoffrey Holmes. Augustan England. Professions. State and
Society, 1680-1730 (London: George Allen & I nwin, 19«2), 4. 9. We
agree generally with Holmes's point, though when a physician was
proposed for fellowship in the Royal Society, the proposal was usually
by another physician, which suggests an element of association.

Cavendish

not necessarily the most important indication of a
scientist's direct contributions.) 28

The eighteenth century was the age of
aristocracy in Britain. Stirring speeches were made
in parliament and bold actions were taken in the
field by men who came from that segment of society.
But Walpolc and Nelson did not come from it. nor
did the leaders of industry and commerce, nor did
the poets, artists, and inventors. A case might be
made that the aristocracy knew its finest hour when
Henry Cavendish delicately laid his standard
weights in the pan of his precision chemical balance.
We conclude our biography by returning to the
beginning, the "Problem." Although Henry
Cavendish left a treasure-hoard of written words on
scientific subjects for posterity, he spoke few of
them to his contemporaries. Lord Brougham, who
knew him, thought that he "uttered fewer words in
the course of his life than any man who ever lived
to fourscore years, not at all excepting the monks of
La Trappe." 29 Johnson said that "words are the
daughters of the earth, and . . . things are the sons
of heaven," and "language is only the instrument
of science, and words are but the signs of ideas." , °
The scientists' credo was the Royal Society's
Nullius in verba, their insistence that the facts of
nature are not bound by any dogma.' 1 Pronounce-
ments of the new philosophy, however, do not help
distinguish Cavendish from his voluble individual-
istic colleagues. Poverty of language was certainly
not at issue, for Cavendish wrote as he worked, with
precision and with complete command of word and
expression. Neither was disinterest in communicat-
ing; that can be ruled out by every thing Cavendish
stood for. Neither, we believe, was Cavendish's
station in society, though a case has been made that
it was. 32 His acute social anxiety is obvious and
certainly contributed to his silent way as did,
perhaps, the family's "hereditary tactiurnity." 33 But
Cavendish's silence had other or additional origins:
we believe that like the Trappists' vow, there was
something chosen about it. Two considerations
have weight with us. We have given a number of
examples of Cavendish's wariness of words, of their
use as instruments of deception. His understanding
of language was in agreement with linguistic
thought in Kngland in the late eighteenth century,
when the object was no longer to reform language,
to make it perfect, as it had been with the founders
of the Royal Society, but to study it as it was used,

as custom i4 . The scientific revolution had revealed
a new world and with it the need for a language of
measurements and abstract mathematical relations,
and in part, we think. Cavendish's silence was an
acknowledgment of the inadequacy of customary
spoken language to represent that world. The
pains he took always to define his quantitative
terms before beginning to reason with them is an
indication of what we mean here. When Cavendish
did speak, as Playfair noted, his speech was always

-'"There were different opinions on the weight to he given to
publication in the eighteenth century, the differences having much
to do with the scientists' occupations and status. When Cavendish
said to Priestley that he did not have a tenth of Priestley's industry in
experimenting and in writing, Priestley took offense, lie lectured
Cavendish: "You greatly overrate both my readiness in making them
/experiments/, and my facility in writing; and may not perhaps
consider that my time is likewise much engaged in things of a very
different nature." Priestley may have had Cav endish, among others,
in mind in the preface to Experiments and Observations on Different
Kinds iij Air. "When, for the sake of a little more reputation, men can
keep brooding over a new fact, in the discov ery of w hich they might,
possibly, have vers little real merit, till they think they can astonish the
world with a system as complete as it is new. and give mankind a
prodigious idea of their judgment and penetration; they are justly
punished for their ingratitude to the fountain of all know ledge, and for
their w ant of a genuine love of science and of mankind, in finding their
boasted discoveries anticipated . . . ." Priestley was probably right in
thinking that Cavendish did not know how he spent his time; by the
same token, Priestley did not how Cavendish spent his. Apart for their
regard lor one another's work in science, w hich was very high. Priestley
and Cavendish probably had little understanding and appreciation of
one another's was of living and thinking. The social gulf between them
was too great. Henry Cavendish to Joseph Priestley, 20 Dec. 17K4,
draft; Joseph Priestley to Henry Cavendish, 30 Dec. 1784; published in
A Scientific Autobiography of Joseph Priestley, 239-42; quotation of
Priestley on 240. The quotation from Priestley's Experiments tin//
Observations is taken from Edward Thorpe's introduction to vol. 2 of The
Scientific Papers of the Honourable Henry Cavendish, F.R.S., ed. E. Thorpe
(( Cambridge: Cambridge I Iniversity Press, 1921 ), 6.

-''Henry. Lord Brougham. "Cavendish," in fives of Men and
letters and Science Who flourished in the Time of George III
(Philadelphia, 1845), 250-59. on 259.

"•Quoted in Hans Aarsleff. The Study of Language in England,
1780-1860 (Minneapolis: University of Minnesota Press, 1983), 122.

"Larry Stewart. The Rise of Public Science: Rhetoric, Technology, and
Natural Philosophy in Newtonian Britain. 1660-1750 (Cambridge:
Cambridge University Press, 1992), 3.

'-'James Gerald Crowther attributes Cavendish's failure to pub-
lish much of his best work to his class and wealth, w hich isolated linn
from the scientists of the industrial age w ho would otherwise have
encouraged him. Crowther's analysis is provocative, but it is too
schematic to be very convincing or helpful. Class and wealth were
important to Cavendish and in many ways, as we have argued. Lord
Charles and Henry Cavendish, for instance, derived stimulus from
their class to enter public work in science, just as, say, James Watt
derived scientific stimulus from his class. "Henry Cavendish." in
Scientists of the Industrial Revolution: Joseph Mark, James Watt, Joseph
Priestley. Henry Cavendish (London: Crescent Press. 1962), 271-340.

"Expression used by I Icnry I lolland. quoted in (jwendy Caroe. l/ie
Royal Institution: An informal History (London: John Murray, 1 985). 39.

"Murray Cohen. Sensible Words: Linguistic Practice in England
16-10-/7X5 (Baltimore: The Johns Hopkins University Press. 1977).
78, 88-96. The vogue of books on prescriptive English grammar in
the late eighteenth century does not invalidate the point made here.

Copyrighted male

/// Conclusion

"exceedingly to the purpose, and either brings
some excellent information, or draws some
important conclusion." 35 Davy put it forcefully:
when Cavendish did choose to speak, what he said
was "luminous and profound." 36 On the subjects he
cared to speak about, Cavendish spoke precisely
and sparingly as a point of conscience. This leads
us to our second consideration: silence can be
positive. 37 Young recognized this in his observation
that Cavendish's hesitancy of speech was not a
physical defect but an expression of the "con-
stitution of his mind."™

Cavendish's wonderfully concentrated inner
life was directed to nature, as we have seen, but if
we are right about his music, it was not entirely so
directed. The main task of music, as it was
understood in the eighteenth century, was not to
imitate nature but to imitate the feelings, and of all
of the arts, music was understood to be the art that
spoke most directly to the feelings. 39 Together with
many of his colleagues, through music Cavendish
had access to an expression of feeling that was at
once mathematically precise and distinct from the
mathematics of natural description, one that could

371

stand in for the (for him so difficult) spoken and
otherwise conventionally acted out expression of
feeling. This is not to say that the work of science
lies outside the world of feelings, far from it, but
only to suggest the clearly limited domain of social
experience in which Cavendish might be char-
acterized, as his colleagues did characterize him, as
a man without affections.

This silent man is an endlessly fascinating
figure. Despite the length of this biography, when
all is said and done, the person of Cavendish
remains in large part in shadow. At the heart of the
problem of Cavendish lies the mystery' of human
communication.

"John Playfair quoted in Wilson. Cavendish, 166.

"John Davy. Memoirs of the Life of Sir Humphry Davy. Hart., vol. 1
(London, 1836), 222.

"Susan Sontag. " The Aesthetics of Silence." in Styles of Radical
Will (New York: 1'arrar, Straus and Giroux, 1969). 19-20. 26. Maurice
Merleau-I'onty, The Prose of the World (Kvanston: Northwestern
University Press, 197.5), 4-6.

'""Thomas Young, "Life of Cavendish," in Cavendish, Set. Hap.
1:435-47, on 444.

'''Music and Aesthetics in the Eighteenth and Early-Nineteenth
Centuries, ed. P. le Huray and J. Day (Cambridge: Cambridge
I niversity Press, 1981 I. S, p. passim,

ACKNOWL E DG ME NTS

We express our special gratitude to Peter Day, Keeper of the
Devonshire Collections, and to his associate Michael Pearman for their
valuable and courteous assistance.

In the captions we acknowledge permission to reproduce
illustrations, and in footnotes we acknowledge permission to use
published material. Here we acknowledge permission to quote from
unpublished material in archives: Society of Antiquaries of London;
Bedfordshire Record Office; Trustees of the Natural History Museum.
London; Trustees of the Chatsworth Settlement; syndics of the
Fitzwilliam Museum; Trustees of the Royal Botanic Gardens, Kevv;
Beinecke Library, Yale University (the James Marshall and Marie-
Louise Osborn Collection).

APPENDIX

Officers of the Royal Society

Presidents:

i Jl 1 1 .itlclL. 1 > L» \V IWI I

1727.

Sir Hans Sloane

1741.

Martin Folkcs

1752.

George, Karl of Macclesfit

1 HA.

James, Earl of Morton

1768.

James West

1772.

Sir John Pringle

1778.

Sir Joseph Banks

Treasurers:

1700.

Alexander Pitfield

1728.

Roger Gale

1736.

James West

1768.

Samuel Wegg

1802.

William Marsden

Secretaries (two):

1718-17.

John Machin

1721-27.

James Jnrin

1727-30.

William Rutty

1730-52.

Cromwell Mortimer

1747-59.

Peter Davall

1752-65.

Thomas Birch

1759-73.

Charles Morton

1765-76.

Matthew Maty

1773-78.

Samuel Horsley

1776-1804.

Joseph Planta

1778-84.

Paul Henry Maty

1784-97.

Charles Blagden

1797-1807.

Edward Whitaker Gray

1804-16.

William Hyde Wollaston

1807-12.

Sir Humphry Davy.

Foreign Secretaries:

1723.

Philip Henry Zollman

1728.

Dr. Dillenius and Dr. Sch

1748.

Thomas Stack

1751.

James Parson

1762.

Matthew Maty

1766. John Bevis

1 772. Paul Henry Maty

1774. Joseph Planta

1779. Charles Hutton

1 784. Charles Peter Layard
1804. Thomas Young

Clerks and Assistant Secretaries:

1723. Francis Hawksbce

1763. Emanuel Mendez da Costa

1768. John Robertson

1777. John Robertson (son of above)

1785. George Gilpin

Source: Charles Richard Weld, A History of the Royal
Society.

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Full text of "Cavendish"

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